I've bought a lot on GB, sold some. Most were good transactions, had to fight with one to get my money back, GB will be no help. I had some sellers with inaccurate descriptions; some slightly worse, some big and intentional. I've also been pleasantly surprised the other way. I've learned to only buy from folks with over 10 or so positive feedback and greatly prefer good pictures. I've had better luck with forums, especially for collector items.
When I sold something it was MO only. I have a Paypal account, but I'm not going to risk getting it locked by a bad payment description or something. The seller's description should cover the payment methods, shipping costs, etc...if you don't like the terms don't bid.