Some consideration has to be given to your location. In South Central Texas, I charge $6.75 per square foot as a base price for all supplies and labor---turn key. A relatively simple twin quilt would be roughly $300 at that rate; a complicated pattern or custom quilting would be more. Remember not to 'jump up if you don't intend to run.' That customer will tell another, and another, and another, and you'll end up working yourself to death for a little of nothing and wishing you'd never 'jumped up.' Wanna ask me how I know?