There is great interest in Mononoke, but the 
prices of those cels are most likely too much 
for the average anime cel collector, IMO.

 But give it a try, you may find some collectors 
interested in one, anyway. Especially if you are 
willing to take installments, you may find 
some one willing to buy one.

What do you have?  If it is a great shot of San 
then your chances dwindle as the price goes 
up. 

It all depends on the cel and of course there is 
the rare breed that might actually be able to 
afford one.