I think it would be a thoughtful gift.  One way to 
make it obvous you're not just being cheap is not 
to copy an actual scene from the show or artbook 
image, but to make a "personalized" fan cel.  

You could do something cute like putting your 
friend's favorite characters from different shows 
together, making a romantic couple of two favorite 
characters from the same show, or posing a 
character with your friend's pet/car/etc.  

Alternately, if your art skills are up to it 
(heaven knows mine aren't up to even the simplest 
fan cel!), you could do a really gorgeous pose of 
their favorite character in a nice unusual outfit.

--Atiya