WHILE it may not approximate the romance of bartering at a Mexican open-air market or picking through the junk in London's Portobello Road, thrift and consignment store shopping has its own varied rewards. Where else could you find paperback books for 25 cents, or men's ties for under a dollar? How about a man's wool dress suit for thirty bucks or a woman's raincoat for ten?

Thrift shopping combines the thrill of exploration with the satisfaction that comes from getting a good deal. At most shops, you will never have the feeling that you spent more on something than you should have. Rather, you'll walk out amazed that anyone could sell a perfectly (well, maybe not perfectly) good record player for eight dollars. And, at thrift shops run by charities, you'll know the money you spent went to a good cause.

There are a lot of thrift and consignment stores in the Washington area but two suburbs in particular, Silver Spring and Bethesda, offer so many in such a concentrated area that dedicated and novice thrift shoppers alike can spend a whole day walking among them. Here, then, are two thrifty walking tours:SILVER SPRING

Park your car in the large public lot at the corner of Wayne and Cedar and walk down Pershing Drive (or take the Metro to the Silver Spring Station and walk up Wayne). The first stop on our walking tour of Silver Spring's thrift shops is Pennyworth at 925 Pershing Dr. It's operated by the Grace Episcopal Church and is open 10 to 4 Tuesday to Saturday. It's small, one open room, but tidy and has everything you'd expect at a thrift shop. Some of the items recently for sale: a large, orange-foam, pointing-finger hand designed to be slipped over a human hand when cheering on the Maryland Terrapins, 45 cents; a bucket of men's 15-cent ties; a woman's leather purse, $1.25; a 1,000-piece Big Ben interlocking jigsaw puzzle (does it still have all its 1,000 pieces?), 15 cents. They also have the largest selection of women's dress gloves you've ever seen.

Once you've finished here, exit and walk down Pershing to your right, past Jim Dandy Cleaners. Ahead and to your left, across Wayne Avenue, you will see the All That Is Thrift Shop. On your way be sure to notice the intricate brickwork and martial architecture of the Maryland National Guard Armory on your left.

The All That Is Thrift Shop (946 Wayne Ave., open 10 to 6 Monday through Saturday) benefits the Boy's and Girl's Homes of Montgomery County. Its long, narrow room also has the usual assortment. Among its recent inventory: a paperback copy of Shane, 25 cents; a 12-inch disk of Cheap Trick's "Tonight It's You" (for "promotional purposes only" and probably given free to some radio station), 50 cents; a Mork and Mindy Board Game (for two to four players, ages 7 to 14 and probably appreciating now that Pam Dawber has her own show), 50 cents.

When you've had your fill of All That Is, exit and walk to your right past Montgomery Donuts. Two doors down, at 942 Wayne Ave., is the Prevention of Blindness Society Paris Flea Market and Thrift Shop. Ask yourself whether it actually resembles a Paris flea market and walk in. (Don't forget to leave your bag of merchandise at the front desk.) It's open 10 to 4:45 Tuesday to Friday and 9 to 4 Saturdays. Recent favorites: Everwear American Flag Outfit, $10; red leather chair, $25; 5x7 framed photograph of unidentified woman in horn-rimmed glasses, $1.

You're probably feeling a little peckish about now so it's time for lunch. Leave Prevention of Blindness and walk down Wayne, past the Universal Artificial Limb Co., and stop at Little Tavern. Order two little cheeseburgers with everything from the carryout window at the rear (don't get the big ones; they aren't as good and we don't want to get filled up). Walk right down Fenton, eating as you go, then turn right onto Bonifant Street. Go down about 20 yards, stop in front of 941 Bonifant and observe a moment of silence. Though the sign says THRIFT SHOP, it recently closed. Not to worry, though, directly across the street is the Hadassah Thrift Shop. It has quite a few books along its left wall and several different rooms of merchandise. Recent standouts include: Polaroid Land Camera Highlander 80 Model ("60 seconds from snap to print" says the case, though it will probably take a lot longer to find film for it), $5; LP album of Jimmy Dorsey's Greatest Hits, 50 cents; leather and canvas golf bag, $4; leatherbound copy of The Diary of Samuel Pepys, 50 cents (but I bought it). Open 9:30 to 5 Monday through Thursday, 9:30 to 4:30 Fridays, 11 to 5 Sundays.

Leave Hadassah and walk to your left. If you like, you may buy a hunting license at Atlantic Guns Inc. (No licenses are needed for thrift shopping.) Cross the street and stop at K's Korner, 955 Bonifant. It's a consignment shop, not a thrift shop, so its prices are a bit higher. However, if you're really driven to own used merchandise, look around a while.

When you're done there, walk back to Fenton and turn right. On the far side, at 8223 Fenton, is Family Thrift Shop, sponsored by the Jewish Council for the Aging. (If you've bought any clothes, it's probably a good idea to drop them off at Weller's Dry Cleaners next door.) Family Thrift is open 10 to 4 Monday to Saturday. A recent inspection revealed: men's golf shoes, $3; two-piece gray man's suit, $30; a hardback two-volume set of Page Smith's biography of John Adams, $5; a 1966 Michelin Guide to France, 50 cents.

Sadly, we're done with Silver Spring now. Walk back to your car/Metro contemplating your recent acquisitions. Did you really need them? Probably not, but then again you probably only spent about seven dollars.

Next stop . . . BETHESDA

Bethesda is what Silver Spring is going to look like three years from now. While you were able to park without a problem in Silver Spring, it's probably a bit tougher to find a spot in Bethesda. (Of course, you can take the Red Line.) If you drive, try one of the public parking garages like the one on Waverly Street between East-West Highway and Montgomery Avenue.

If you park there, walk down Waverly toward the Air Rights Building (so called because its builders had to obtain rights to the air over the train tracks it spans). You will notice that there is a big hole in front of the Air Rights Building where Wisconsin Avenue should be. Don't panic; they're fixing it. Walk down Wisconsin past the Montgomery Farm Women's Cooperative (call 966-3303 if you want information on when it's open) to 7125. This is the Montgomery County Thrift Shop, open 9:30 to 4:15 Monday through Saturday and staffed by volunteers from six nonprofit organizations. Check to make sure you aren't carrying any food or bare feet and walk in.

If you've just come from Silver Spring, you may be a bit shocked at how neat and tidy it is inside. This is Montgomery County, after all. The main room is the thrift shop. It has a nice assortment of clothing, though there are very few books. To the left and down the steps is the two-room consignment shop. Things are a bit more expensive in here but there's usually an interesting assortment, including: not one, but two different Queen Elizabeth II memorial silver jubilee coffee mugs, $12 and $16 (for the diehard anglophile, there is also a QEII napkin holder priced competitively at $12); and a brass "art deco" (I'm not so sure) smoking stand, $10.

When you're done in here, walk out and back up Wisconsin Avenue. Cross at the light and walk down Bethesda Avenue on the left side. All around you you'll notice the construction that grips Bethesda. You may also notice the Wagon Wheel Restaurant on the right. It's surrounded by concrete partitions and roadworkers, like a lonely island in a sea of construction. Farther down, on the left, in a collection of low, modern stores, is the Opportunity Shop (4848 Bethesda Ave., open 10 to 4 Tuesday to Saturday). The money you spend here will benefit the St. John's Norwood Parish. If you do decide to buy you'll notice it's a bit pricier than some thrift stores. Everything also seems to cost $12: two- burner hot plate, $12; small child's BMX-style bike, $12; leather briefcase, $12. (To be fair, there was a set of nice fireplace andirons for $19.)

Unlike Silver Spring, Bethesda doesn't have one thrift shopping district. Bethesda's other shops are all near St. Elmo, Cordell and Norfolk avenues. The physically fit can walk, though: Continue down Bethesda Avenue and turn right on Arlington Road toward Old Georgetown Road. As you walk, ponder some of the problems the modern thrift shop encounters. One is a shortage of volunteer staff. Most thrift shops are run by volunteers from non-profit or charitable organizations but it's tough to find people who have the time to sit in a musty thrift shop during the day. Some have taken to hiring professional staff. Also, many people won't donate to a thrift shop unless their giveaway can be picked up. But most thrift shops don't have the resources to keep a truck on the road, so they appreciate it if you can drop your donations off. Resolve to do just this as you cross Old Georgetown and walk down St. Elmo Avenue. (Note: Not all thrift shops accept donations every day; many have set aside certain days for donations. Call ahead.)

Next to New, at 4918 St. Elmo Ave., isn't a thrift shop, but it does sell quality used clothes. It has mostly women's fashions and they're on the expensive side. However, you can finance your purchase: It's one of the few shops that accept credit cards. (Open 9:30 to 5 Monday through Saturday.)

When you're done at Next to New, continue down St. Elmo and turn left onto Norfolk. At the end of the block you'll pass the U.S. Nuclear Regulatory Commission. Turn left onto Cordell Avenue. At 4912 Cordell is the Think New Consignment Shop. You'll know it by the somewhat disrespectfully decorated bust of George Washington in the window. Once you're past the narrow first room (jewelry, women's clothes) and pokey second room (shoes), you'll find another room that's cavernous. It's filled with clothes, knick knacks, household items, etc. Everything is labeled with accurate if mundane descriptions (such as "eagle ashtray") and prices ("$4.50"). They have a nice selection of women's coats, including, recently, a trench coat priced at $22. (Open 9:30 to 5 Monday to Saturday.)

Across the street, at 4907 Cordell, is Reprise, a good name for a thrift shop. It's run by the Jewish Social Services Agency, is open 10 to 5 Monday through Friday and sells mainly women's and children's clothes. (They also have "over-the-fence tennis balls," four for a dollar. They're exactly what they sound like.)

When you're done at Reprise go back up to Norfolk and turn left. You may notice the sign across the street that says "Bank Your Own Blood." Wonder what this world is coming to then walk down to Identity Crisis Consignments at 8000 Norfolk Ave. (On the way you'll pass a strange non-functional portico set into the wall at 7952 Norfolk. If you've brought a camera, have your picture taken in front of it.)

Identity Crisis Consignments is the last stop on our tour and an identity crisis is what you may have after examining the belongings of so many other people. It's open 11 to 6 Monday through Friday and 10 to 5 Saturday. It stays open 'til 9 p.m. on Thursdays. Identity Crisis also accepts credit cards and, for some reason, American Express Travellers Checks.

If you've walked to all these thrift shops, now you'll probably wish that you had driven. Of course, Bethesda and Silver Spring aren't the only two Washington suburbs that are home to thrift shops, but they're the only two with the sort of high concentration that makes walking possible. They're also undergoing such changes that the Bethesda and Silver Spring we know now may not be around in the future. (Those interested in even more thrift shops should check out the dozen or so that are spread out in Arlington, several of which dot a two-mile stretch of Arlington Boulevard. For even more, look in the Yellow Pages under "Thrift Shops.")

And when you've found that perfect item -- whether it's a pair of patent leather go-go boots or a Super 8 movie projector -- remember that you earned it and you wouldn't have found it anywhere else.

Washington free-lance writer John Kelly went through college wearing other people's clothes.