Notice my edit above. He opened the case against you. You can not open a case against him now. If you do not buy the bike it goes as a mark against you. To many of those and you can get kicked off ebay. You still have buyer protection through Paypal if you go through with the purchase at the agreed upon price. If he backs out he gets a bad bad mark. Ebay is very hard on sellers. Buyers get away with murder.