Persepherone's has been my go to place recently. Great prices and super quick shipping. They are also very friendly when I had to call with a question.
http://www.persephonescreations.com
I frequent Ft Worth Fabric Studio also. They also have great customer service and super quick shipping.
http://www.fortworthfabricstudio.com
i shop at Form & Fabric too. They have $2.99 flat rate shipping on all us orders. Great clearance prices too!
http://www.formandfabric.com
And because I like to support the independents, I buy often from Etsy.com