that's an interesting point...

I do sometimes try to do that, but I often fail 
miserably. I buy cels becuase of the character 
or emotion or beauty of the cel alot of the time, 
but often, the cel is incomplete (ie, the 
character is cut off by some other character 
that isnt in the cel, leaving a strange cutout on 
the character)
or perhaps its not a nicely centered cel, or 
maybe the character is very small.

often I can stop myself from buying a 
mediocre cel though by saying "would I like to 
frame this"
becuase some things look alot better framed 
than others,... its an interesting criteria as to 
what cels to buy and what not. and definitely a 
way to save money. although, I'm not haveing 
much success following my own advice :)