NOT SO LONG ago, youngsters purchased packages of baseball cards as much for the bubble gum inside as for the players' pictures, many of which ended up as noisemakers attached to bicycle spokes.

Other cards, stashed in old shoeboxes under beds and in closets, met tragic fates at the hands of parents cleaning out their grown children's rooms.

Today, some savvy kids wouldn't dream of being so careless, because collecting and trading sports cards has become much more than a casual pastime. Young collectors study monthly price guides and frequent card shops and dealers' shows to stay on top of the hottest players. They don't just buy baseball cards; they invest in them.

"Years ago, collecting baseball cards was something you just didn't talk about. You weren't a nerd, but it was something to chuckle about," says Duane Harris, president of NOVA Sports Cards in Manassas. Now, he says, "kids are proud of the fact they collect cards."

"It's really an investment and a hobby," says 11-year-old Ryan Bliss of McLean, who, after a year of serious collecting, has amassed about 10,000 cards. "I collect cards because it's fun -- it's a lot of fun -- it's interesting and you get a lot of money."

Bliss and other collectors follow monthly price guides to keep track of cards' changing values, determined by what both dealers and collectors are willing to pay. They want to buy low and sell high.

"It's very similar to the stock market. These prices are changing, sometimes hourly when something is very, very hot," says Harris, who, like many dealers, belongs to a computer network that helps determine pricing.

Young hobbyists generally realize, however, that cards seldom turn collectors into millionaires. Even when expounding on the hobby's investment potential, few kids overlook the fun side of card collecting.

Fifteen-year-old Carter Cromartie, a collector who works at Jeff's Baseball Corner in Springfield, is quick to point out that only 500 of his 20,000 cards are worth anything.

"The rest are just basically cards of your average Joe Schmo," he says.

Bliss says he also appreciates limited-value cards. "I enjoy collecting the guys that I like and seeing what kind of pictures they have and what their batting average is, and just collecting in general."

Most serious young collectors concentrate on obtaining rookie cards of current popular baseball, football, basketball and hockey players. At prices that start around 50 cents, youngsters today can buy wax packs, individual cards or boxes containing packages or singles, produced by a growing number of companies that have joined 40-year-old Topps, the traditional favorite.

Cromartie says the hottest card right now is a 1989 Ken Griffey Jr. rookie card made by Upper Deck, a new sports card company that's proving popular with kids. "It's a year-old card and it's already worth 30 bucks . . . . {Griffey's} probably the hottest prospect in the game right now."

While many youngsters are reluctant to sell their coveted new cards, most collectors trade frequently with friends.

"We got together New Year's Eve and I think were up till 4 in the morning," 15-year-old Chris Gibbs says of a recent trading session with friend and co-worker Cromartie. Gibbs recently gave Cromartie a 1990 Griffey card in exchange for a stack of hockey cards in which Cromartie had little interest.

Linda Monfort, an eighth-grade math teacher at Ben Franklin Intermediate School in Chantilly, supervises an after-school Sports Card Collectors' Club, now in its third year. Monfort says the hobby helps children learn the important skill of negotiation.

"It's like watching little businessmen of the future, because they will sit there and they will talk to a person and then they will say, 'No, I'm not happy,' and they'll walk away," she says. "It's like watching someone trying to buy a car."

For many collectors the hobby is a shared activity between family members or friends. Gibbs and his father, Jim, collect cards together and buy hobby-related gifts for each other. For Christmas, Gibbs bought his dad several 1959 cards of his favorite team, the White Sox, who won the American League pennant that year. Gibbs received from his father a Topps set from 1975, the year Gibbs was born.

Card-collecting also runs in the Bliss family, where Ryan, 10-year-old Lisa and 7-year-old Nicholas pursue the hobby, along with their father, Robert, whose mother threw away the shoeboxes containing his childhood collection. Each person is trying to build a set of Upper Deck cards; they trade their doubles.

Ronny Siesser, 14, of Silver Spring, recently divided a collection he had kept with best friend Dani Gorlin. The eighth grader says he expects to taper off his collecting once he enters high school.

"But I do plan to give the cards to my kids," he says. IN THE CARDS

Dealers of sports trading cards and memorabilia gather for shows at area hotels just about every weekend. In addition there is a show epecially for young collectors. The third annual Children's Baseball Trading Card Show will be held May 4 from 10 to 4 Wakefield Recreation Center, 8100 Braddock Rd., Annandale. Although anyone may attend the event, vendors must be under age 18. A 7-by-10-foot space costs $15 and may be reserved by calling the center at 703/321-7081.

The following local shops specialize in sports trading cards, hobby supplies and sports memorabilia. THE DISTRICT SCAVENGERS OF GEORGETOWN -- 1210 31st St. NW. 202/338-0077. Open 11 to 5 Monday through Thursday and 11 to 6 Fridays and Saturdays. Open some Sundays.


Corner of Fourth and Florida avenues NE. 202/546-7020. Open 6 a.m. to 7 p.m. weekdays and 6 to 5 Saturdays. MARYLAND ANYTHING COLLECTIBLE -- 969 Ritchie Hwy., Severna Park. 301/647-5222. Open noon to 6:30 Tuesday through Friday and 10 to 6 Saturdays. BETHESDA DUGOUT -- 8227 Woodmont Ave., Bethesda. 301/986-0111. Open 11 to 7 weekdays and 11 to 6 Saturdays. BONANZA BASEBALL AND SPORT CARDS -- 8433 Georgia Ave., Silver Spring. 301/585-8630. Open 10 to 6 weekdays and 10 to 5 weekends. COLLECTORS CHOICE -- Laurel Center, 368 Armstrong Ave., Laurel. 301/725-0887. Open noon to 8 weekdays, 11 to 7 Saturdays and 10 to 4 Sundays. GOLDEN EAGLE COIN EXCHANGE -- 9125 Riggs Rd., Adelphi. 301/439-1444. Open 10 to 6 Monday through Saturday. HOUSE OF CARDS -- 2411 University Blvd. W., Wheaton. 301/933-0355. Open 11 to 6 Mondays, Wednesdays and Fridays; 11 to 8 Tuesdays and Thursdays; 11 to 6 Saturdays and 11 to 4 Sundays. ROCKVILLE STAMP AND COIN -- 1097-F Rockville Pike, Rockville. 301/251-0021. Open 10 to 5 Mondays, Wednesdays, Fridays and Saturdays; 10 to 8 Tuesdays and Thursdays. SPORTS EXCHANGE -- Antique Centers 1 and 2, 8600 Foundry St., Historic Savage Mill. 301/470-4373. Open 10 to 5:30 daily. VIRGINIA ACE'S BASEBALL CARDS -- 1113 W. Church Rd., Sterling. 703/444-2255. Open 3:30 to 7 weekdays, 11 to 7 Saturdays and 12 to 7 Sundays. AJ'S SPORTS STOP -- 255 W. Maple Ave., Vienna. 703/938-1688. Open 10 to 7 weekdays, 10 to 6 Saturdays and 12 to 5 Sundays. Also: Ballston Common, 4328 Wilson Blvd., Arlington. 703/243-7996. Open 10 to 9:30 Monday through Saturday and noon to 6 Sundays. A1 -- SACKS ARE LOADED -- 5741 Burke Center Pkwy., Burke. 703/250-1749. Open 11 to 8 weekdays, 10 to 6 Saturdays and noon to 5 Sundays. BJ'S BOOKS -- Waterloo Shopping Center, 381 W. Shirley Ave. at Route 29, Warrenton. 703/347-4111. Open 10 to 8 Monday through Saturday and noon to 5 Sundays. BRANT BOYS BASEBALL -- 220 Loudoun St. SE, Leesburg. 703/777-5801. Open 11 to 7 weekdays and 10 to 6 weekends. THE CADDY SHACK -- (formerly K&L Baseball Cards) 8733G Cooper Rd. (at Route 1), Alexandria. 703/360-4303. Open 10 to 8 Monday through Saturday and 11 to 5 Sundays. CAPITAL COMICS CENTER -- 2008 Mount Vernon Ave., Alexandria. 703/548-3466. Open 11:30 to 7 Monday through Thursday and Saturdays and noon to 8 Fridays. CARD COLLECTORAMA -- 2008 Mount Vernon Ave., Alexandria. 703/548-3466. Open 11:30 to 7 Monday through Thursday and Saturdays and noon to 8 Fridays. CENTURY STAMPS AND COINS INC. -- 6436 Brandon Ave., Springfield. 703/569-0739. Open 11 to 5 Mondays; 11 to 6 Tuesdays, Thursdays and Fridays; 11 to 7 Wednesdays; and 10 to 6 Saturdays. JEFF'S BASEBALL CORNER -- Ravensworth Shopping Center, 5222 Port Royal Rd., Springfield. 703/321-7550. Open 10 to 8 weekdays, 10 to 6 Saturdays and noon to 5 Sundays. NOVA SPORTS CARDS -- 8813 Commerce Ct., Manassas. 703/368-0312. Open 10 to 8 Monday through Saturday and noon to 5 Sundays. SPORTS BOOKS ETC. -- 5224 Port Royal Rd., Springfield. 703/321-8660. Open 10 to 8 weekdays, 10 to 6 Saturdays and noon to 5 Sunday. THE SPORTS PAGE -- 765 Elden St., Herndon. 703/481-3134. Open 11 to 9 weekdays, 11 to 6 Saturdays and noon to 5 Sundays.

Mary Jane Solomon last wrote for Weekend about holiday shopping centers for children.