I have been reading this thread with interest to 
both side of the argument.  But I agree with Star 
Phenoix:

Cel collectors own the physical cel; while the 
studio owns the rights to those characters.

So, legally fan cel creaters doesn't need to have 
consent from the cel collector who owns the cel
(but it's a curtesy to ask).  On the other hand, 
they have BIG legal liability to the studio for 
creating characters FOR PROFIT without license 
from the studio.  Note "FOR PROFIT"!  Studio 
doesn't care if poeple draw their characters for 
fun, but they do have problem when people profit 
from their characters without share profit with 
them.

As matter of fact, I think Ebay would be liable 
for those "bootleg" items.

Further thoughts?