I don't know about others but I have sold, quilts that I make just for the pleasure of making a quilt, for $1000. And a Queen for $600. If a person wanted me to make a specialized design I have done even a baby quilt for $250. So much depends on the cost of material and mostly my time. I don't often make quilts for people to be sold. That's not my thing right now. The majority of my quilts go out as gifts that are well appreciated by the recipient.
One other thing about making a quilt for someone else I learned along the way is a "contract"! Even the best of minds don't visualize things the same way. One thing I also learned is to make sure you get a 50% 'non-refundable deposit with the other 50% due on deliver or you keep the quilt! Other aspects of a contract will be interesting for another thread. I am sure someone here has a copy of their contract that they can share.