I am going to second craftersvision.
They have some of the best selection and prices for designer fabric online!!
Here are a couple more but they are a little more expensive:
www.jcarolinecreative.com- this one has great free tutes too!
REPRODEPOT FABRICS - vintage reproduction fabrics, retro fabrics, japanese import fabrics, unusual fabrics, plus retro and vintage look buttons, ribbons, patches, patterns and sewing supplies - RETROFABRICS.COM
bnbmom- Michael Miller is one of my faves too!