Trunks is a pretty popular character, and the 
bidder might be legit.  I mean, how many nice 
Trunks cels do you see out there with any 
background at all much less a matching one. And 
you definitely don't see them too much on e-bay 
or the American market in general.

Whoever it is might not get to the really good 
updates fast enough and are willing to pay for 
the time and effort you put in to get it. Either 
way, it's definitely worth a shot!

Beside, there had to be at least 2 people who 
thought it was worth the price.  If the first 
bidder flakes, you could always offer it to the 
second. Even if they don't buy it at their final 
bid price, you might be able to negotiate a deal 
where you knock a $100 off their high bid. That 
way, you are getting a deal, and so is the bidder!

By the way, is this the same cel someone was 
offering you $50 for and was unhappy that you 
didn't consider that a fair price?

Good luck with your auction!