Sorry, but 1,000 Bolts does not sell by fat quarters, only whole yards but they do have it sorted by color. Connecting Threads has their Quilter's Candy basics and they will cut quarter yards, you just specify fat or linear.
I did a quick search of some online shops that will sell in quarter yards and I went through about half my list and found that Missouri Quilt Company will also.
http://www.missouriquiltco.com/