My friend and I are going to Europe in August and we're in the same boat as you. For myself I found the easiest and best deal is to just rent a motorcycle in Czech Republic, Prague. I'll be renting a CB500 for 8 days and it's about $550 Eur (insurance + helmet included). The only downside is that I have to return it back there so my trip will be a loop. My friend on the other hand is landing in Spain and riding all the way to Romania so he's looking to buy and sell. My friend has done some research on the buying and selling, but he's had no luck finding a good bike yet. I'll see him tonight so I'll tell refer him to your post maybe he can help. Cheers!