I wouldn't be so quick to run from this one if you really like the bag. Even outside of ebay, PayPal offers some buyer protection (I don't know specifically what it is but you can look it up on PayPal's site).
Bonanzle is so new that you are bound to come across buyers and sellers who have no feedback. But how is this person supposed to get feedback without selling? It's a vicious circle. I'm new to Bonanzle and I would hate to think that people think I'm selling fakes just because I don't have any feedback yet.
I think as long as you have the bag authenticated here, email the seller and ask if they have an ebay ID you can check for feedback, and make sure you are comfortable with PayPal's protection for out of ebay transactions, then I don't see anything wrong with buying from them. Just cover your bases first!