Hey,
Not sure if you figured out how to signed up, but I was just reading the help pages:
http://pages.ebay.com/help/buy/ebay-bucks.html#signup
and it seems that you need to purchase an item that is qualified for 'ebay bucks' (there will be an icon on the page of this item you bought) and after this you will need to receive an invitation from ebay to sign up to ebay bucks. From what I understand you can't sign up without the ebay invitation. Hope this helps you somehow
