Any other craftsperson, whether carpenter, photographer, cake decorator, etc., would require some type of deposit, so why shouldn't you?
About 5 years ago, a co-worker asked me to make a quilt and she thought I was trying to scam her on the price I quoted her - $100 for a twin. We found a pattern and fabric on-line and discussed the yardage required. I gave her links to, I think Hancock's of Paducah, for the fabric, batting, and thread, so she could get the prices for herself. She told me the next workday that she had changed her mind.