TC Custom Carts Chambersurg ripped me off

I sell industrial shelving and racking . The owner of this company called me several times looking for some, but I have had a hard time keeping it in stock. The end of August I got a lot of racking in and call these people. The owner came up and picked up a bunch of racking. The bill came up to $1400.00. I had already given him prices on the phone before hand, so it should not have come as a surprise how much he would have owed. He gave me $700 cash and I told him he could mail me a check for the balance. If this would have been a homeowner, I would not have done this, but I couldn't imagine that a business owner would risk their reputation over $700. I called him a few weeks after he was supposed to send a check and he said that he had bought a little more than he needed. I told him- no problem, bring it back and I will give you every penny of your money back. No one ever bought any back. I emailed a reminder invoice over a month ago, sent a copy in the mail, and left a message weeks ago and told them that if they were having financial problems, please let me know and I would work with them. I have heard nothing from them. Once you start ripping people off it becomes part of your mentality. I would not do business with these people.