Be very careful. If you don't enjoy doing it, it will become a second job that you dread, then you will dread seeing the person you are making it for. Personally, I'd show her how you made yours and offer to help her make the quilt for her daughter. If you are still stuck making it, then have her buy all the materials needed at the very least.
I'd also show her sites who make t-shirt quilts professionally, like this one:
http://www.lovethemquilts.com/ You can check out her pricing and some of ones she's made.