The evening didn't get off to a promising start. First, the tuxedos almost didn't arrive. Then she spilled champagne on her off-the-shoulder pink satin gown. And, worst of all, after she stepped out of the rented Lincoln and headed for the door of the Tysons Corner Marriott, her date locked the keys in the car.

But Trisha Dixon said the cost of dinner at Clyde's for herself, her date and another couple, the Lincoln, the photographs and the clothes were all worth it. After all, it was senior prom night for Fairfax County's W.T. Woodson High School, and no extravagance was too great for the once-in-a-lifetime evening.

"It's worth it," she said Friday night. "I've bent over backwards to get it perfect."

For Washington area high school seniors and their families, it's the season when the bills start rolling in for all the events and trimmings that make up the perfect senior year. With yearbooks, class rings, photographs and the prom -- not to mention graduation itself and attendant partying -- the package can run $500 and more.

"We're talking a lot of money," said Bill Doran, a senior at Woodson High School. "You don't think about it, but it does add up."

The price is rising, and not just because of inflation. Proms once held in school gymnasiums hung with crepe paper now take place in rented hotel ballrooms. Guests often arrive by limousine to make a splash -- and to avoid the risks of drinking and driving. Seniors can now buy two yearbooks, one the traditional paper version, the other on videocassette.

Mary L. Wade, a senior class adviser at Gwynn Park High School in Brandywine, says senior mementos don't have to bankrupt students. However, she blinked hard when she saw the price tag on a solid gold class ring ordered by one of her Prince George's County students.

Decorated with special inscriptions and set with an expensive stone in a sunburst pattern, the ring cost $238. Wade talked her charge into a more modest version.

"It doesn't have to be that expensive," Wade said of senior fever, "but they all want something different."

Steve Rye and a Woodson classmate planned to rent a Cadillac for $75, which a junior friend offered to drive to the prom for free. Other Woodson students hired their brothers and sisters to drive them.

At Walt Whitman High School in Bethesda, students may buy a videocassette of the year's magic moments -- including a shot of their "alphabet group" receiving diplomas -- for $30. The tape runs 2 1/2 to 3 hours.

Some seniors take extra jobs to underwrite their expenses, since some parents will go only so far to support their desire for the extravagant items. Jim Bartelloni's parents gave him the rental fee for his prom tuxedo, but the Woodson senior wanted a top hat and cane too, so he cut lawns for a weekend to earn the required $30. "You gotta go first class," he said.

Others, like his classmate Eric Schmidt, have it easier: "My parents paid for everything. They gave me the credit card," he said.

But there is little grumbling about the financial outlay, even from students who pay themselves. Most seniors appear to want the works, even though most of it -- including attendance at graduation -- is usually voluntary. After all, senior year is magic and, as Sydney Jones, student government president at Calvin Coolidge High in the District, put it: "You want to make your last year your best year."

A senior year shopping list includes:

Class ring: Basic price is about $65, but elaborate versions go for $150 and more.

Yearbook: $20 to $30. Ten dollars buys a yearbook photograph, but most students order packages costing $30 to $60. Add another $5 to $8 for a class picture or photograph of the student being handed a diploma.

Prom: Dance and dinner at a hotel prom runs about $40 a couple. Many students shell out $80 or more for dinner for two at posh restaurants rather than go to a hotel dinner. Prom pictures and a "memory book" cost from a few dollars to $50.

Transportation: An evening in a rented car costs from $30 for a basic drive-it-yourself model to $350 for a chauffeured Rolls-Royce, sometimes equipped with telephone, television and bar.

Clothing: Woodson's Denise Connor had her prom dress made for $40, and Jill Philips borrowed a gown from her mother. A store-bought frock runs from $95 to $120, and a complete get-up of lace gloves, lace stockings, dyed-to-match shoes and an evening purse is another $60 or more. For boys, tuxedo rentals are $45 and more. Prom corsages go for $15 for roses, half that for lesser blooms.

Graduation: $10 for cap and gown rental, although some schools let students use hand-me-downs from brothers and sisters. Graduation announcements -- "You send them to relatives and they send you money," said Sandra Ducharme, a senior at Robinson Secondary School in Fairfax -- run anywhere from a quarter each to $40 for a set.

Some schools offer graduation packages. At the private Sidwell Friends School in the District, $30 pays for flowers, invitations, chairs, food, programs and diploma at the ceremony. Students do not wear gowns. At Calvin Coolidge High School in the District, students are charged $92 for a picture, yearbook, cap and gown and diploma.

Parties: Schools discourage students from renting hotel rooms for post-prom parties, but students do it anyway. Gwynn Park's Wade won't estimate how many students book rooms: "They don't tell us," she said, "and I don't ask."

Then there are the after-graduation parties; one set of Woodson parents is renting a community pool. Seniors plan on spending $100 for the traditional "beach week" at Ocean City, Md., after graduation. Some schools have senior banquets at various prices; Walt Whitman's was $20. Some have class trips; Walt Whitman's trip to the Bahamas will cost $260 per student.