For hawkers like Samuel Rogosky Jr., buying and selling half-fare airline coupons may just have been practice.

"The next big thing will be gas rationing coupons," Rogosky says. "It will make all this look very small."

Rogosky has been sitting in front of United Airlines' city ticket office on K Street NW for months now seeking to match -- for a profit -- those who wanted to procure the discount airline coupons with those who wanted to get rid of them.

The coupons were the promotional brainchild of United Airlines, seeking an innovative way to lure customers back after its crippling two-month strike in the spring. American Airlines then matched the United plan.

Under the program, half-fare coupons were distrubted to any passenger who flew on the two airlines during the first three weeks following the end of the United strike -- May 28 through June 17. The coupons were good for a 50 percent reduction on a regualar or first-class ticket for travel between July 1 and midnight Dec. 15.

Because the coupons were legally transferable, a brisk trading business materialized almost overnight as individual entrepreneurs like Rogosky and professional commodities traders such as California-based-A-Marked Financial Corp. saw opportunities for profits.

Although he declined to say how much money he's made, Rogosky said yesterday, "it's been worth-while." Once selling the coupons for as much as $60, his sale price this week was down to $5.

Rogosky, a Montgomery County cab driver when he's not in the coupon business, was the only coupon dealer in sight yesterday, eiher downtown or at the airport. He admitted he hadn't made a sale since Wednesday and is stuck with five or six coupons for each airline. "I'm here mostly out of curiosity," he said.

A-Mark, a precious-metals traders based in Beverly Hills, went into the coupons in a big way. Andrea Haveman, director of A-Mark's coupon program, said they had a little more than 40,000 of the coupons and have just a couple hundrend left. It bought most of them at airports in June from passengers who had just been given them at an average price of about $20 -- and sold them for an average price of $55.

Haveman said the company doesn't yet know how much money it will have made, though, because as many as 10,000 of the coupons were supplied to the United States Government, travel agencies and some businesses on consignment.

A spokesman for General Services Administration said yesterday the federal government will have spent a total of $417,815 on nearly 10,000 coupons from three firms which it distributed to the 40 federal agencies that said it could use them. The Government will only pay for what it has used, however, and may be returning some of the coupons to the firms. The GSA spokesman said figures are not yet available on the money that might have been saved the taxpayer because government employes used half-fare coupons. Federal agencies were instructed to use the coupsons on the longest trips to maximize the savings. The Department of Transportation had asked for the most coupons: 1,855.

Redemption of the coupons was far below what the airline originally estimated. A United spokesman said yesterday that about 65 percent of the 2.5 million coupons distributed will have been turned in; United originally predicted an 85 percent turn-back rate. "Many coupons probably wound up tucked in a wallet and forgotten about and a lot of others probably went through the laundry," a United spokenman said.

A spokesman for American Airlines said that between 50 and 60 percent of the 1.8 million coupons it distributed will be used.

Officials of other airlines and industry analysts have questioned whether the coupon promotion was a bottom-line success, but officials of both United and American say it was. The number of new passengers generated by the coupons more than offset losses suffered because some passengers who would have traveled anyway at higher fares were able to travel for half, they say.

A spokesman for United said the airline made a record recovery from the strike; carrying 23 out of every 100 domestic passengers before the strike, United increased its market share and was carrying 24 out of every 100 just two months after the strike. "No airline ever recovered that fast from a strike," he said

Albert V. Casey, chairman and president of American Airlines, said yesterday it was definitely "worth it" to have matched United's promotional program. "We know we gained" he said. "Just imagine if just United had the coupons during the soft traffic period." The coupons were drawing customers to United and American while their competitors, like Trans World Airlines, were suffering a reduction becausae of the sluggish economy, he said. Last month, for instance, airline traffic for both United and American was up between 13 and 15 percent over November a year ago, while traffic for TWA was down 8 percent and many other airlines also saw declines.

"But you can quote me on this," Casey added. "I'm glad it's over."

While the big coupon programs for American and United are over, several other airlines still have some limited coupon programs in operation, and limited programs in the future are likely.