I like to make t-shirt quilts. just finished one last week. I like to add shashing and a cornerstone so I have to make sure that all the blocks measure exactly in this case 14.5 inches. I have made about 6 and have been paid $160 - $300 depending on size and wheather they brought fabric or not.
I first took a class on making these t-shirt quilt and that really helps because it gives you confidence to quote a price. With fabrics at $13 a yard it is more expensive now, please do not short change yourself.