What happened to honor, integrety, respect?

A couple of months ago, I sold a coin on ebay to a fellow who, it seemed from the start to be a little sly. Now, I sell a few coins on ebay, mostly, coins that don't make the grade for my sets. I've never had problems before, so an expert in sale issues, I am not. This time though, it seemed that he just wanted to buck the terms of the sale from the start. Firstly, let me tell you about the terms of the sale. The item was to be paid in U.S. dollars, through paypal, and within 3 days. I try to be a nice guy. After about 5 days, I send a message to him asking for the payment. I get a response that he'll send a check. Not my terms, but what the hay, it's not for much money anyway. Only $9.99 U.S. including the $6.00 shipping. So, I lost on the coin, you win some and you lose some. About 1.5 weeks later, I get the cheque. For $9.99 Canadian. write him and ask him for the rest, about $3.00 more Canadian. His response was that he would send the rest when the coin arrives. I wait to make sure the cheque clears, and then send the coin in good faith, after all, it wasn't alot of money anyway. I thought that this guy was a bit screwy from the start, after all he had broke every sale requirement that was posted with the sale. I just wanted the transaction done with. I wait another 2 weeks and then politely message him asking if he had recieved the coin. He had I guess, because I never got a message back, but the feed back he placed for me was nasty. So nasty, that he had even attacked me personally, using words like "whiner seller, lier " etc.. As you can tell it was negative feedback. I, at this point asked him why he did that. His response was that he did not feel that he should pay for that much shipping and handling, and wouldn't pay. So much for seller terms, paypal, and in U.S. dollars. I sent the coin in good faith. Mind you, I did decide to scimp on the shipping due to all the goings on. I guess now, rightfully so. So now a couple of more weeks have gone by, the customer still bitter, negative and just as nasty. I decided to move on. I posted a non payment with ebay against him, stopped the talking back and forth. Offered him his money back, for the coin back, and tried to get my positive nature back. He was dragging me down. I then even stopped communicating with him. All for $9.99. Sometimes I wonder if it's just me, or what happened to the deal with a handshake. I guess the good old days are gone.