Majin Vegita is one of the more "sought after" of 
the DBZ characters - he's only possessed 
and "Majin Veg" for like 9 episodes.  I have like 
11 cels of him M. Veg and I have gotten some very 
good deals on some (most of those over a year 
ago - prices have hit the roof since then..), and 
paid high amounts for others.  It depends on the 
individual cel - if you either post a pic of the 
cel in question, or email me with it I'd be happy 
to give you my opinion. (I don't claim to be an 
expert or anything... ^_^  Just have some 
experience buying M.V.)  

A good rule of thumb is that if it is either a 
close up in good condition, or a cel where he's 
powering up (with the yellow airbrushing for 
his "ki" around him) it's going to be more 
expensive.  I don't really consider backgrounds 
to be worth all that much more since about 90% of 
Dragon Ball cels aren't matched to correct 
backgrounds. :)

But then again, I've spent more then a cel is 
really "worth" just because I like the scene it's 
from, or else I just really like the look of it. 
^^;;

Hope that's some help! :)

SWolf