If it doesn't seem like the person would be 
closed to offers, then you can make one. I think 
you might also consider telling the person how 
you feel about the cel and why. . . You never 
know if it might tip things in your favor. It at 
least lets them know why you want specifically 
*THEIR* cel instead of another cel of the same 
character/series.

One thought to ponder: When making offers on cels 
in people's collections, I wouldn't just offer a 
good "going rate" for the cel. Your bet bet is to 
think up what the going rate might be and add at 
least 20% - or more. You're asking for something 
from someone who didn't intend to sell - not from 
a store - and the extra underlines that you 
understand such. ^_^  Not to mention that it 
makes your offer more tempting overall. ^_^

(Another thing that can't hurt if you're not sure 
the person would be receptive to an offer is to 
*ASK* if they're interested in hearing an offer. 
Tell them how you feel about the cel, that it's 
your dream cel, etc, etc, and tell them you'd 
like to make an offer to them for it, would they 
be interested in hearing one?)

Many Sharp Smiles,
--Drac