If you enter the quilt in a judging competition and win then you may have some credentials to charge. Someone who doesn't have experience in a particular skill cannot charge too much for the time. What would you be willing to pay for it?

I think $250 would be more than fair. Or, if you wanted a quilt like that,Dunstar's idea is a good one. Past experiences have proven to me that if you do not charge anything for your work, the work will not be valued.
Good luck!