With the deadline for using American and United airlines half-fare coupons only four days away, remnants of last summer's army of dealers, traders and sellers were busily trying to unload their remaining coupons yesterday but finding few takers.

"I'll take anything for it," [a leftover return ticket from Washington to San Francisco, bought with a coupon] said Cynthia Snyder, 23, as she stood by the United Air Lines ticket counter at National Airport, pleading with passengers as they bustled by.

"I'll sell it for $100. I'll sell it for $75," she said.

"I haven't had any takers," said a forlorn Ken McPherson, 18, a University of Maryland student standing nearby, trying to sell two United coupons for $10 each.

Professional coupon dealers such as Samuel Rogosky, 34, who has been swapping, selling and buying at his informal sidewalk office in the 1700 block of K street NW since last August, said the coupon businesss has slowed down and is now almost finished.

There's been no last-minute surge of sales, he said, just a few people stuck with leftover coupons trying to get rid of them.

"I'm not buying anymore," he said yesterday. He says he still sells a few coupons ( $25 each this week; $35 last week), but he's about to fold his office in front of the United ticket office at 1725 K St.

"Most people who fly have already made commitments," he said. "They're already bought their tickets a long time ago."

During a 20-minute period at noon yesterday, Rogosky got no buyers, but about a half-dozen people offered to sell-coupons to him. He turned them all down. "I don't need to get stuck with a lot of leftover coupons," he said with a shrug.

Rogosky, a Montgomery Country cab driver when he isn't selling coupons, told one woman with a coupon to post a notice on the bulletin board at her office. "Ask $5 for it," he said. "Maybe you'll get something out of it."

Nick La Rosa, United Air Lines passenger service supervisor at National Airport, said there has been no flurry of coupon users as the Dec. 15 deadline approaches.

"If anything, there's less activity," he said. " . . . I think that the people that were going to use them have already used them."

The coupons were issued last spring by United Air Lines in a promotional effort to recover passengers lost during a 58-day mechanics strike. American Aielines immediately matched the offer to retain the passengers it had gained from the United strike.

This is the way it worked: between May 28 and June 17, every passenger who flew on either of the airlines was given a coupon entitling the bearer to buy a round-trip ticket to any point in the continental United States for half the regular coach or first-class price. The coupons and any tickets purchased with them had to be used between July 1 and Dec. 15, and were nonrefundable.

Issuance of the coupons triggered a brisk secondary business throughout the summer, in buying, selling and trading coupons by travel agencies and freelance dealers.

Cynthia Snyder, the woman with the leftover ticket to San Francisco at National Airport yesterday, was typical of many other passengers who were not dealing in coupons for profit but simply got stuck with an unneeded ticket.

"I flew here from San Francisco last Sept. 21" on the first part of a round-trip ticket bought for half price with a coupon, said Snyder. "I'm not going back now (as originally planned), "and now I need somebody to use it before the deadline."