The Cotton Loft
http://www.quiltingcotton.com/ prices can not be beat! I know a while back they were slow to ship because they were inundated by the board because Patrice posted about them. But I just ordered recently and had my order within a week! All of the fabrics were LQS quality! 1 yard minimum but after 1 yard you can order in quarter yard increments
I also like thousands of bolts
http://www.thousandsofbolts.com/
Full yard cuts only
Fabric Depot but they do seem to take a bit longer for me because they are on the other side of the country
http://www.fabricdepot.com/
Some of the closeouts have a half yard minimum. Fabric depot is a little pricier then the others but they have a wonderful selection and the closeout areas are more then fairly priced with Batiks at $6 per yard. If you catch them during a sale you can get their regular batiks at between $7 and $8 per yard. Right now they are having a superbowl blow out sale with a bunch of gorgeous batiks at $5.50 per yard. GROAN
And I have also had good luck at Whittles
http://www.whittlesfabrics.com/cgi-bin/Store/store.cgi