Despite all the hype and hoopla, all record prices aren't set in auction houses. Two weeks ago Milton Avery's widow, Sally, received a phone call from a New York dealer saying that a major Avery, "Bathers by the Sea," had just been sold for $300,000 -- the highest price ever paid for a painting by this unique American artist, who died in 1965, having received far too little recognition.

The highest price paid during the artist's lifetime was $16,000 -- and that only happened once. In the '50s his paintings were priced at less than $1,000 and didn't sell.

"There were years when Milton sold only one painting at $100. It was rough," recalled Mrs. Avery, in town last week for the opening of a show of Avery paintings and watercolors at Lunn Gallery. For her, the "Bathers" sale was more than just a record price; it was a personal triumph. Since her husband's death she has devoted herself "to showing the world what a wonderful painter he was," just as she did during their marriage, when she, as an illustrator, supported the family so that he could paint full time. "I hated to let the 'Bathers' go, but the price had to be established," said the savvy Sally Avery.

The well-deserved posthumous buildup in both prices and recognition has come, in fact, largely through her careful orchestration of the unsold works her husband left behind. She has released only a few paintings and watercolors each year through select dealers, including Lunn, and has over-seen the publication of a lavish new book on the artist, just published by Strathcona Press. She is now helping the Whitney Museum put together a major Avery retrospective for fall 1982, which will travel around the world, and will no doubt push prices ever higher.

"I knew he'd be recognized one day," she said.

The Lunn show is small -- 16 works -- including a dozen watercolors and four large oils, most of them typical Avery landscapes or seascapes reduced to quintessential contours and flattened masses, and defined by muted, intuitive color.The major painting here, vintage Avery, is "Speedboat's Wake," a night-blue sky over a dark sea interrupted by gentle whitecaps and the white parabola of the title, a characteristic bit of monumentalized whimsy. In his watercolors, Avery used a sort of linear shorthand to sum up his feelings about his subjects. "Speedboat in a Choppy Sea" is one marvelous example, as is "Birds by a Dappled Sea," wherein he captures flight in a few spare lines.

For collectors who can't afford five- and six-figure Avery paintings and watercolors, Lunn's print room is offering several of Avery's equally enticing drypoints, lithographs and woodcuts for prices between $200 and $2,500. All are illustrated in the catalog raisonne of Avery's graphic work, published by Lunn in 1973 in conjunction with the Avery print retrospective at the Cororan.The show continues at 406 7th St. NW through June 30.

In his most impressive show to date, Washington printmaker Percy Martin is exhibiting an ambitious new suite of color etchings at Gallery 10, 1519 Connecticut Ave. NW. Conceived as a series, these images depict events in an epic fable, invented by Martin himself, which deals with the evolution of mankind from what he calls "bushmen" to civilized adult citydwellers. It's not all that specific, but that's the general story line.

To play out his narrative, Martin invents a whole pantheon of character, chief among them the many "bushmen" (read Everyman) who must, for example, levitate and touch the back of sacred birds and elephants in order to fulfill the Rites of Adulthood. Sounds odd, but the idea lends itself, via Martin's fertile imagination, to semi-abstract imagery that is a delight. Several prints are entitled "Touching of the Sacred Elephant" and depict human figures floating over elephants and birds.

To understand what's going on in several other prints you know the catechism: "St. Mar" is a spiritual being and former mortal bushman, "Nova" a High Priestess of the Bushman Sacred Society, and "Avon" (Nova's twin), a priest in the Temple of St. Mar. Brenda, the scoundrel in the lot, rejected the rules of the Sacred Society, and was therefore rejected by the Sacred Bird. "The Rejection of Brenda II" is one of the most intriguing prints.

The configurations in these etchings -- human and animal figures exaggerated into pure decorative line -- are highly sophisticated here, far more so than in any of Martin's earlier work. But it is the addition of rich, deep color layers of muted mauve that sets the best works apart. Here, imagery and color come together with greater subtlety and expressive power than ever before. This would seem to be the beginning of the mature work of Percy Martin. Ther show closes today.