Washingtonians who fill up their tanks and drive the 3 1/2 hours to the "Colonial Capital" in Williamsburg often find themselves wandering down Duke of Gloucester Street with nothing but a Colonial Williamsburg Foundation (CW) brochure in hand. Complete with dining, hotel and sightseeing suggestions, the pamphlet is designed to attract visitors, or "touri" as William and Mary students affectionately call them, to Foundation-owned or sponsored attractions.

The CW restaurants, shops, hotels and tours are for the most part extremely well done and worth seeing. The colonial atmosphere is faithfully reproduced and the food's quite good at the colonial restaurants - The King's Arms, Christiana Campbell's and Chowning's Tavern. A constant diet of colonial cuisine from these establishments, however, can put a large dent in a family's vacation pocketbook, as can the Foundation's current admission prices, and the prices in the privately owned shops in nearby Merchant's Square. According to a recent CW brochure, a family of four can count on spending $200 per day for lodging, food and tours offered by the Foundation.

But visitors need not spend their life savings for a Williamsburg vacation. The key to finding the reasonably priced or even free attractions in Williamsburg is to venture off the well-beaten cobblestone path, discard those beautifully photographed CW Foundation brochures, and discover the Williamsburg that the college students and "townies" know.

A few suggestions for avoiding high tourist prices and some of the summer crowds:

Don't automatically buy an admission ticket. Many visitors don't realize that they can see quite a bit of Williamsburg without a ticket. The main streets are always open for walking, and, as the students demonstrate, for joggina and biking as well. Take a leisurely stroll down Duke of Gloucester Street - you can enter many restored buildings without a ticket. Bruton Parish Church, the Silversmith Shop, the Post Office and several colonial shops are all free to visitors. Don't miss the bakery for freshbaked gingerbread at twenty cents a cookie.

To avoid crowds, try walking down treelined Francis Street, or Prince George Street, both running parallel to Duke of Gloucester. Don't forget William and Mary's old campus, including the Wren Building, the Sunken Gardens and the Crim Dell, selected as one of the top college romantic spots by Playboy magazine.

If these long walks leave you and your faimly thirsty, resist the temptation to grab a soft drink at one of the drugstore counters in Merchants's Square - you'll pay up to twice as much as you're used to paying. Instead, walk one block over Prince George Street, where The Cheese Shop has canned drinks for reasonable prices, as well as a good assortment of juices. High's Ice Cream across the street also sells soft drinks for less than the counters on Gloucester Street.

Hungry for a quick sandwich? The Cheese Shop also sells take-out sandwiches from 11 a.m., to 2 p.m. Monday through Saturday. Their French bread is tops, and be sure to ask for the house dressing on the sandwiches.

The College Delly on Richmond Road is another good place to grab a bite, offering a greater variety of subs and indoor seating. Sandwiches borrow their names from William and Mary dorms and customs, adding some local and collegiate color. You'll have to supply hour own chuckle if you order a "hot co-ed to go." They've heard it before.

If you want a slightly bigger meal for lunch or dinner, try George's Campus Restaurant on Prince George Street. "George's" is a favorite of college students and offers about the most food for the money anywhere in town, if you stick to the daily specials. Entree, two vegetables, bread, tea or coffee and ice cream or rice pudding runs about $2.50. Breakfast is another money-saver - an egg, toast, hash browns and coffee for under a dollar.

The atmosphere at George's is - well - unpretentious, but the food is good and you're guaranteed to encounter a fascinating mix of accents, from Greek to Spanish to West Virginian. Students have been known to order green beans for dinner simply to hear waitress Mary's motherly order barked out in an incredible West Virginia twang: "Taste your beans before you salt 'em!"

Sunday brunch at the CW-owned Cascades restaurant is a real treat, but is often crowded. To avoid the throngs, drive out Jamestown Road to the Chickahominy House for a good Southern Sunday Brunch. Or, for a real treat for the kids, continue on Jamestown Road and take the ferry across the river. The Surry House on the other side provides good colonial and Southern food at reasonable prices.

If you're determined to get some authentic colonial culture, but don't like the high prices and limited selection of the Duke of Gloucester Street restaurants, eat dinner elsewhere end go to Chowning's Tavern for "gambols" after nine. The gambols include colonial singers and musicians, free peanuts and an assortment of alcoholic and non-alcoholic drinks and snacks. Ask the games hostess to teach you the colonial "Goose Game," or, if you prefer, stick with blackgammon or checkers. The gambols provide all the fun and atmosphereof Williamsburg without the high price nf a colonial dinner.

If you're a real tennis buff, there's no need to pay higher prices for a hotel with tennis facilities. Lighted public courts are available at Quarterpath Park off Route 60 and at other facilities in town.

If the family is planning a day at Busch Gardens, pack a picnic lunch. Unlike the rival Kings Dominion, the Old Country does allow food to be brought into the park, and provides a picnic area as well. Bringing your own food will save a bundle over the high-priced park food, and will rescue you from thoese long lines at the food stands.

Resist buying scented soaps, candles wooden gifts in the high-priced gift shops. Instead, plan to stop at the outlet stores that line Route 60 on the way out of town. If you can brave the weekend crowds, the bargains make it worth a stop.

Williamsburg is a beautiful town. Luckily, it need not be off-limits to those who cannot afford the high prices of the C.W. Foundation attractions. By going a little out of your way, and by living "as the natives do," you and your family can enjoy the colonial capitol and still have enough money to pay for gas to get home. CAPTION: Picture 1, WILLIAMSBURG'S DUKE OF GLOUCESTER STREET; Picture 2, THE GARDENS OF THE REBUILT GOVERNOR'S PALACE