i don't think you can have "too many." i think 
that if you're looking to sell some cels to make 
money or make room in your cel books, then you 
could limit your collection by the means others 
have suggested here. but personally, i don't 
think that there is any such thing as having too 
many cels (points at yann) ;).

i think it's probably easier if you have cels 
from the same sequence, to just keep the one 
that you want and sell the others. that way, you 
have the character you like in different 
poses/outfits, and not just one sequence of that 
character. just some thoughts...

haruna