I dont see why it's a big deal at all.  I think 
as long as you state it's not an authentic 
production cel, then it's cool.  I dont know why 
collectors get so bent out of shape over people 
using their cel images...if you own the cel and 
it's in *your* book at home, what difference does 
it make if someone uses the image or makes a 
repro of it?  I dont get it, never will.  I 
watermark my cels so that people will know where 
the cel is located at.  I dont care what they do 
with the images.