I have been commissioned to make T-shirt quilts, queen size, tied every 3". The client had to provide the T-shirts I provided all other material and charge $450. This was several years ago. Today I would charge $500. If you look on line for places that do it that is the common going rate. They are quite a bit of extra work because you have to put some sort of interfacing on each T-shirt so the blocks won't stretch out of shape in the piecing process. They sew together quickly but the prep time is what gets ya.