If your supplier's sales rep is being unusually cooperative these days, it could be that he's just a terrific guy. Then again, it could mean that you're paying more than you should for your materials. "A supplier's job is to get as much as he can whenever he can get away with it," notes Anne Hallenbeck of A & B Associates Inc., a procurement-consulting firm in Wilmington, Del. Your only real protection is to line up an alternative supply source, which can provide you with another perspective on what's happening in your marketplace. Hallenbeck, in fact, advises checking in with the backup at least once a quarter. "That doesn't mean that you need to buy from second sources," she says. On the other hand, you probably can't keep them on the back burner forever, so you should probably figure on sending some business their way sooner or later, or finding some new backup sources.