I've discovered some new to me places from searching this site:
http://www.quiltshops.com/
It's really helpful if you are looking for a particular fabric. I usually click on the advanced search option and select to view images. Then, you can click on each one and see their prices, check the shipping.
There are shops out there that offer free shipping for orders over $30/35. SeaWatch Fabrics is one, and their regular prices are less than the quilt shops. Their collections are more recent releases than some of the ones with more discounts.
One of my new favorites is Desperate Quilters. The collections are more recent and prices pretty good.
Really good discounts are available at Thousands of Bolts or Whittles. Great sales at Over The Rainbow.
There are many to choose from. Have fun exploring!