Paul Saffo is a futurist with a headache.

Saffo, director of a Silicon Valley think tank called the Institute for the Future, is an influential tech pundit, but he has to get in line with the rest of us when it's time to cash in on rebate deals.

Take a CompactFlash memory card from Lexar Media Inc. that he bought in March. The card works fine, but he's still waiting on the $40 rebate from Lexar he was promised when he bought it.

His first claim was rejected because he gave his return address as a post office box. Subsequent calls -- most recently in June, July and August -- have been fruitless as well. "I don't care about $40," he said. "But it's become the principle of the thing.

Diane Carlini, a spokeswoman for Lexar, said via e-mail that the company couldn't address Saffo's problem without having the specifics of the case. "We strive to fulfill each and every rebate offer issued for Lexar," she said.

Rebate offers abound in the consumer electronics marketplace -- it's not hard to find products that cost nothing after rebates.

For retailers and manufacturers, these offers are a quick and easy way to adjust prices in a cost-conscious market. There's little difference between one memory card and the next, so shaving a couple of dollars off can lead to a spike in sales.

But instead of trimming a product's price, companies can offer a rebate and get much of the same sales increase -- without a corresponding dip in profit. How? Only about 60 to 80 percent of customers send in claim forms for rebates, according to a firm that processes many of these forms, TCA Fulfillment Services Inc. of New Rochelle, N.Y.

The effort needed to get those rebate dollars back into the checking account has been a sore subject among consumers for years, and the situation doesn't seem to be getting much better.

David Heim, deputy editor of Consumer Reports magazine, recently bought two computers, a high-speed Internet connection and a printer for his kids. The purchases also got him eight rebates with a combined value of $300.

Though he hasn't received the rebates yet, he has spent a lot of time filling out the required paperwork. "It was easier to do my taxes," he said.

And like taxes, rebates don't seem to be on the verge of vanishing, even if a few retailers, most notably Wal-Mart, eschew rebate promotions.

"It's hard to see them going away anytime soon," said Stephen Baker, an analyst with research firm NPD Group Inc. He said companies find them "a pretty useful way to drive people to specific products."

Companies that offer rebates typically hire outside firms such as TCA Fulfillment Services for the work of collecting claims and mailing out rebate checks. The company handles rebates for about 300 manufacturers and retailers.

When the rebate process is working at its quickest, consumers can expect to get a check in six to eight weeks. But what about those rebates that slip through the cracks?

TCA President Frank Giordano said that his company regularly gets calls from people asking about their rebates. Giordano said that missing checks are usually the consumer's fault for not filling out paperwork or forgetting to mail it in.

"We're not motivated to lose mail," he said. "We've been accused of that very often, but it makes no sense," he said. "If we lose mail, we don't get paid."

Herndon resident John Shepard is unconvinced. Shepard got an e-mail this summer from TCA Fulfillment Services, saying that a rebate check for $20 was on the way to him -- for a cable modem he bought from CompUSA Inc. over three years ago. He's still calling CompUSA for the money and said he got a fresh promise from the company for the rebate money on Friday afternoon.

CompUSA did not return phone calls or an e-mail request for comment. Giordano, however, said his records show that the company sent Shepard a check for that rebate in January 2002, a mere half-year or so after Shepard bought the cable modem. Shepard, saying he doesn't remember getting any such check and noting that TCA itself seems to think he's still owed it, asked, "Why would they pay me twice?"