The Fat Quarter Shop is awesome for finding out about the new lines of fabric. They have just about everything. And I love their fat quarter sets. BUT-- their prices are a little high.
The Quilt Home is pretty cool, too if you can't find something somewhere else they may have it. And they ship for free if you spend over $50 (VERY easy to do!). But again, higher prices.
The best place I have found to buy designer fabric is on Etsy. Here are some of my favorite sellers.
LanieJaneFabric- Love her fabric picks! Also, she makes precuts in various fabrics for you. FANTASTIC!!!
Fabric Supplies- Very good prices, LOTS to choose from!
DownShadowLane- Another good one.
Sew Love Fabrics- She sends a few cute little charms in various fabrics with your purchase! How cool is that?
FabricBee- She has some fabrics I can't find anywhere else.
And once in a while I find something on Ebay. But usually it is overpriced. Oh, and all of these Etsy sellers will refund any overcharge in shipping. Very nice.
Hope that helps, Lace. But you can't blame me when you get addicted!!! ;0)