The 3 day law is only good for door-to-door salesman. At least, here in TX. I know, because I researched this once for my daughter who purchased something and couldn't return it (not a quilt; returns are not required by law and there is no 'Buyers Remorse' law here). However, she was stuck with it, due to the non-existent 3-day Buyer's Remorse Law here in TX that she thought would cover her. I don't know about other states though.
I have friends who create beautiful quilts on commission, and they always ask for 1/2 non-refundable deposit, and have a contract terminating a clients interest should the quilt not be paid for within 15 days of completion. They also spell out they are free to donate, sell, give away, or keep the quilt if not paid for in full within the 15 days.
I wouldn't hesitate to get 1/2 deposit - I think $100 isn't enough, but 1/2 would at least cover the majority of your financial investment in the quilt - not the time, of course, but the fabrics, thread, etc.
Debbie in Austin