Balloons! Assorted T-shirts - a big variety of colors, styles and funny mottoes! Coasters? Playing cards! A set of highball glasses? Buy an umbrella before you go outside!A fine selection of budget jewelry, something for everyone on your gift list. Someone you know would love a needlework kit! Souvenir key-rings, just fifty cents, proves you've been here! Now - what you need is a tote bag, to carry it all home in!

The fine arts have discovered the fine art of merchandising. These wares are spread out under the crystal chandeliers to catch balletomanes and operagoers whose pockets are jingling during an evening of high culture.

The slightly lower cultures have known for years how to turn audiences into consumers. Disney films have put out so much merchandise for so long that the other Mickey Mouse items are being hawked as antiques. "Star Wars" is a cottage industry with a special line of toys for Christmas, and "Turning Point" is scheduled to become another. No self-respecting rock star would miss the opportunity to sell the fans a little something to take home.

But until fairly recently, nobody had paid much attention to the buying power of people who could fork over a lot of money for high-price entertainment. The libertto of the opera or some photographs of the dancers were all you could take home from the culture center, unless you count memories.

Now every company which has a choreographer also has a merchandise manager or boutique director on the staff.

The merchandising centers are in New York, but this year many companies have started putting together small general stores to take on the road. It's unbeatable publicity for a show to have people walking around town wearing, in effect, sandwich boards advertising the attraction.

And the best part is that the living posters pay for the privilege. For some retailers, like the Friends of the Kennedy Center, the extra income goes into special educational projects that would not be possible without it. Others use if for general support of the company.

Rosalie Lewis, Gift-Bar Coordinator for the New York City Ballet, figures that custom-made toe shoes cost the company about $11 a pair, and she can re-coup part of that by selling them, used and autographed, for $5 a principal's pair, $3 a soloist's and $2 for a pair from a member of the corps.

Merchandising has become a significant factor in the life of the Metropolitan Opera," said Geoff Peterson, whose mail-order business in Metropolitan-associated items is expected to gross $700,000 this year but is, he said, "still in its infancy."

Ranging from an $825 music box that plays the Triumphal March from "Aida" to bits of clothing made out of old costumes to 20 plastic glasses with opera quizzes on them for $4.50, the Met catalog has "pretty much touched on everything we can think of," and will be expanding its book and record offerings, rather than "going into shower curtains," said Peterson.

Providing an esoteric selection of culture-related books and records is also the aim of the Friends of the Kennedy Center, which runs stands in the halls there, said president Lily Guest, but the hottest sellers are Kennedy Center key rings and balloons.

Much of the Kennedy Center souvenir business is in items sold to tourists who never see a show, said Guest. The Friends netted $165,000 last year, mostly from "kids who come in with more change in their jeans than you'd think," and foreigners who go off with a surprising number of busts of John F. Kennedy for $35 or $65.

All of the items sold are supposed to have some relation to the center or the arts, but sometimes the connection gets lost. Japanese paper wallets were stocked originally because they had pictures of Noh actors on them (Noh theater has never played the Kennedy Center, but never mind), but when the popular item was restocked it had other designs and sells just as well.

When the American Ballet Theater moved into the Opera House this week, its boutique manager, Valerie Van Winkle, had to select items from its vast stock to peddle at the center and in a co-ordinated sales effort with Bloomingdale's.

ABT not only does a booming business in T-shirts, tote-bgags and notecards (available in Mikhail Baryshnikov, Ivan Nagy, Natalia Markarova and Cynthia Gregory, the last being allowed to run out because the dancer did), but pins ABT buttons on a set of entirely un-dance-related puppets and moves them well at $5 each.

(The risk of obsolete articles affects them all. The National Symphony Orchestra, which concentrates its selling efforts on its annual radiothon - aprons and pseudo-Gucci bags with the National Symphony name will be featured this year - still has a few leftover "D.C. Is Dorati County" T-shirts among its well-selling Rostropovich items.)

A hot seller for ballet companies is used toe shoes, autographed by the dancer, but Van Winkle isn't bringing any here because she has a hard time getting them.

Dancers keep promising them to me, but bizarre things happen to them - they get stolen, or accidentally thrown out," she said. "The fact is that a lot of dancers have a prejudice against people seeing their dirty toe shoes."

The New York City Ballet, however, sold $9,500 worth of merchandise - jigsaw puzzles, stationery, T-shirts, post cards - just in the two weeks before its "Nutcracker" opened this year.

"I always say we can't go any further, but every year we do." said Lewis, who started as a volunteer selling "$16 worth of posters on a good night" and now has 40 to 50 volunteers who have to sell so fast that they don't bother checking indentification with personal checks because it isn't worth the time.

Carey Mackesy, who is the Joffrey Ballet's Junior Boutique sales director, won't sell toe shoes "because I'm afraid some little girl is going to put them on when mommy and daddy are away and hurt herself," stocks $10 wool mufflers as well as T-shirts, tote-bags and buttons, and is constantly getting into different things." Joffrey has offered some souvenirs since it was founded, but just last year started taking large amounts of merchandise on the road with the company.

Shirley Barton of the New York City Opera says that ballet companies have an advantage "because they seem to have younger audiences, who are more interested in things like T-shirts." Nevertheless, she expects the opera company to make $20,000 this year in guest towels, polyester scarves, belt buckles, coasters and, yes, T-shirts and tote bags.

"Ballet, theater and opera are attracting a much broader spectrum than 15 years ago," said Albert Golub, who has the concession that sells show-related items in the Kennedy Center foyer and National Theater lobby.

"It all started with the souvenir books, the programs. A person comes in with the idea of buying a souvenir. If he buys a poster, he might buy a program." Very few buy as they come in, because it means having to hold on to the item during the show.

In Washington, his wares are more apt to be related to a company than a particular show. "Usually, nobody prints up a program or a T-shirt pre-Broadway. You wait until after six or eight weeks of try-outs to make sure it's going to e a hit."

An exception here was "Annie": after two weeks of rave reviews and sell-out performances, the producers went ahead with the program, record and T-shirt.

But road company shows of Broadway hits come well-equipped with merchandise. "A Chorus Line," "Porgy and Bess," "Bubbling Brown Sugar" and "Grease" all arrived with their retail stocks.

But The Friends of the Kennedy Center is ready for companies who haven't thought ot it. All those foreign company T-shirts here in the last two years - La Scala, Paris Opera. Stuttgart Ballet, Berlin Opera, Australian Ballet - were designed locally.

They sold wildly - La Scala T-shirts were snapped up by Kennedy Center employees, ranging from executives to stagehands, "because we were all so proud that La Scala came here," said Guest, and then spread to audiences and building tourists.

And a great many of them went home to Milan in the luggage of singers, who couldn't find such a bargain in their own baroque halls.