If you want to get paid for your time, conversation should go like this -
"can you make two quilts for these two sisters?"
"yes, I usually get $X.xx for a quilt that size, and fabric costs $X.xx, are you sure you want to spend that much?"
Gives them an easy out if they are NOT willing to spend the money, and gives you a commitment if they are willing.
I have said this before on the QB, what is it about us that makes us want everyone to like us? If someone expects me to work for free, I don't really care if they like me or not. Tough tooties. My time and expertise has VALUE - if I choose to gift it to someone I will, but I am not going to be a doormat to make someone else happy.
Now that you are already hip-deep in the situation, is there anyway you can get something "In-kind" from the requester? in other words, if she makes cakes or does taxes, for instance, ask for something from her in return.