cels have no intrinsic value nor are they legal. 
Its not like you can say oh this golf club or 
Grace Family wine is currently valued at $1230. 
and obtain a policy that can cover it and 
additional future value. Cels at best can be 
classified as novelty items and coverage IF ANY 
would vary from state to state. You also might 
want to email dealers directly and ask them 
privately since they too must cover their 
merchandise somehow, lest a fire break out and 
their whole $100k investory go up in a blaze of 
glory.

Also check with Nolo Press Self-Help Legal books 
at the nearest bookstore. I personally don't 
insure my cels, they are expensive BUT these 
aren't investments in any sense of the word 
"investment". If they can be insured its 
reasonable that you'd only get what you 
originally paid (with plenty of documentation 
mind you xerox the cels and the receipts) for it 
UNLESS there is additionally coverage available 
for novelty art items like cels. 

Remember these aren't like Disney or Flisher 
cels, these type of cels have not and more likely 
than not aren't catalogued anywhere. Even 
expensive as hell hanken mono's which big 
collectors like Yann or Curt got aren't recorded 
as sellable licensed merchandise. Why? B/c if 
anyone recalls CELS and HANKEN MONOS ARE ILLEGAL. 
You and I do NOT own cels nor the image nor the 
use of them. They are legally owned by the 
companies that created them. So once again how 
you'd insure them since they are NOT license 
products I wouldn't know, and in all honesty I 
doubt you can & personally I wouldn't bother.