can't help with a contract but for pricing, the average t-shirt quilt would cost approx. $300 depending on how many shirts involved and if they want specific quilting. If you google t-shirt quilt prices, you should run across companies that make these as their business.
I've also read that $16-$18 per shirt is another guideline.
I've made a couple (vowing never to make another one) as gifts so haven't needed to deal with actual customers. But I was asked recently how much to make one, when I quoted $300-$400 depending on the number of shirts, I haven't heard back from either of the people....and that's just fine with me since I don't really enjoy making them.
Oh, and the quotes I gave only included "very" simple straight-line quilting to hold the quilt together.