Good luck Pokergal. I have followed this thread to see what happens. I agree with the last posters, don't take a check, cash only. Fire off an email now telling her $126 is the expected CASH payment and nothing less will be accepted. Don't let her take advantage of you, she has already tried and obviously won't stop now.
PS, I am doubly appalled at her behavior when you told us she is an artist and does custom murals. What we do is absolutely no different expcept our paints and canvas are fabrics and thread. She should be ashamed of herself trying to low ball you on the cost like that.