I think you have to iron - out all of the requirements before you start on this project. Point out all of the costs and labour time involved and have an honest talk with each other. A lot of people, who are not sewers, buy the most inappropriate material that is difficult to sew and quilt. So I think you need to stipulate the type of fabric needed and mutually come to an honest price. If your friend is reluctant to pay the price, you don't need to work for slave wages. You don't have to go ahead with the project if either of you is unhappy about some aspect.You can diplomatically point out that you are unable to do the project. If she gets it professionally done it will not be cheap for quality work in any case. Good luck with your negotiations.