On any contract, I would also be sure to state that the quilt must be picked up and paid in full by XXX days after completion. Otherwise, it will be kept, sold to pay the expenses or donated, at your discretion. This keeps you from holding onto one for 6 months or 2 years, waiting to be paid, or going to court to recoup your expenses. Unfortunately, this happens to many quilters, piecer's and longarmers. Most longarmers generally have this in their contract now. An ending date is a good thing to have!
Good luck with your project!