When you purchase a cel, you are spending hundreds --
perhaps thousands -- on a unique image that is one of a 
kind.  Once that image has been posted all over the
Internet, the novelty value goes down a bit; it becomes
slightly less "special."  Would you be more likely to purchase a great cel you've never seen before (and not many others have laid eyes on) or a cel that has been seen all over the 'net?  

I'm not trying to take one side or the other, but I would
respect the wishes of the person who spent all the money
to acquire the cel.