Small companies have a tough time getting long-term pricing arrangements from vendors. But there's a way to combat vendors' price increases, according to Viktor von Mertens, purchasing manager at $3-million Plastics Plus Technology Inc., in Ontario, Calif. After being notified of a price hike, von Mertens will invite that vendor's sales rep in for a meeting and tactfully inform him or her that a price change is unacceptable. He presents a list of other vendors he can turn to if the price increase takes place. If forced to switch, von Mertens does so as soon as possible. If he's forced to live with the increase, he speaks to the rep's boss so he can better explain the increase when it's passed on to Plastics Plus customers.