>How do we know they are legit?

You don't. That's why most of us only make these 
kind of transactions with people we're familar 
with; the most recent being Anime Chaos, Oion and 
Leigh.

I enjoy Silent auctions. It's given me a chance 
to purchase cels that, had they been for direct 
sale, I would have missed out on. Plus I wont 
have to say "No, not for sale/trade" because no 
name are given.