Don't get stuff framed at a craft store.

If it's a really expensive cel, and you're 
worried about preservation/conservation issues, 
go to a real art gallery and have a person who 
knows something about art take care of it for 
you, as opposed to the high-school kid who 
happens to know how to use a mat cutter and a 
glass cutter but doesn't happen to know about how 
to treat art. ;o) They'd be able to tell you 
about options like UV-filtering glass and vacuum 
sealing.

If it's not something you want to treat like a 
museum relic, there's nothing that a craft store 
can do for you that you can't do for yourself. 
^_^ Buy a frame you like. If you buy glass 
separately, be careful--- they're not always cut 
properly, and there may be some wiggle room. Buy 
a pre-cut acid-free mat in a craft store. The 
matting will keep the cel from pressing up 
against the glass, and the acid-free part will 
keep the cel from being damaged by the gases the 
paper lets off. Buy acid-free photo corners and 
some kind of acid-free backing. Use the corners 
as a nondestructive way of keeping your cel from 
slipping around in the frame. Seal it all up, and 
ta-da. There are more details and more 
instructions in the archives if you do a search, 
but that's the basics. ^_^ You could probably get 
a nice little setup for about $50 if you go all-
out... much less if your frame is simple. The 
biggest cost will definitely be the frame.

Good luck,
-Cres