Businesses don't like paying the processing fees to run a card. 1.5- 4% is a lot that they don't make. It may not matter to the sales staff, but to the owner it does. He probably also has some creative way to get that cash straight in his pocket and the bike out the door without reporting it or paying the sales taxes on it. If you can get to the owner, he will be able to make any deals he wants to.