I'm with nesuferit... kinda. I did an averaging 
once, a while ago on my collection, and I was 
about $100-$150 per cel. (That is an insane 
amount now that I think about it ^^;;;;;;;;;; )

The least i've ever spent was like.. $5 or 
something. The most was, well, just over a grand. 
Considering the priciest one was my dream cel, I 
doubt I'd ever spend that much again. Also, the 
next cost below my dream cel was $275. I really 
try to keep my cels at $100 or less. ^^; 

And yes.. I also have to restrain myself on a LOT 
of these gorgeous cels that creep up. I try to 
tell myself "i'm not the biggest fan, i'm not the 
biggest fan, i'm not the biggest fan...", but 
then the artist in me tugs and whines saying "the 
art on that makes it worth it, the art on that 
makes it worth it, the art on that makes it worth 
it.."

Oi.. what a battle. Good luck with your cel 
purchases :D

~Tara