I like the idea but it won't last long, no offense. Once eBay hears about it they will ban it. You need to physically have an item to sell to sell it on eBay...
Not true at all. You can sell all kinds of digital items including domain names and ebooks. You can also sell codes for game content and time on xbox live, serials for software etc.
Bitcoins are a little different as they are a currency.
However as some others have posted here, a good work around is to sell a physical item like a paper clip and include a "Bonus" of 10 bitcoins or whatever.