Looking for another source of cheap and on-target market research? Donald L. Beaver Jr., founder and chairman of New Pig Corp., has found one: disgruntled not-quite customers. He calls them not-quite because though they use his products, they decide not to pay for them.

Here's how Beaver's plan works. To sell prospects on the Altoona, Pa., company's "pigs" -- devices that absorb leaks around manufacturing machinery -- he offers 20-day, no-risk trials. If you don't like the pigs, you can ignore the bill. When a bill is ignored, Beaver calls to find out why. The result? Ideas for new or improved products. One customer, for instance, said he wasn't paying because his pig reacted with the nitric-acid leaks it was absorbing. Beaver explained that the product hadn't been designed to deal with hazardous fluids -- and set about developing one that could. Today, he says, the resulting hazardous-materials pig is a $2-million-a-year product.

The key to the strategy, Beaver says, is the ignore-the-bill offer. Without it, dissatisfied customers would pay up the first time but never order again, and their immediate feedback would be lost.