College professor David Persell just wanted a bottle of paint sealant that he could apply to his car on his own. But, he says, no car dealer or rust-proofing shop would sell him one. On the theory that other do-it-yourselfers might also choose to buy the product without the service, he tracked down a major manufacturer of the stuff and set up bottling in his basement. Diamond Brite Inc., in Lansing, Mich., sells through retail chains in the Midwest.

-- Leslie Brokaw