[RBS] what to charge for copyright to paintings?

[Rivka Radonsky SLP]

t to charge Chanukah Sameach!
I went today to a printer shop to fill orders for prints of my paintings. 
The owner of the shop wants to buy the rights to use some of my picture 
files for bencher/birkon covers, etc.

He asked me what I am charging and is not making me an offer...does anyone 
have an idea of what I should ask for?

Many thanks
Rivka