There are a few stores I shop at often online. Vitacost is one of them. They have a great gluten-free product selection. They often have sales in their gluten-free department and you'll save an additional 15% off their already low prices. And whatever size order you place ships for only $4.95 and orders over $49 ship for free.
Vitacost will often beat amazon as far as pricing on gf flours. New to Vitacost - use this link
and save $10 off your first order.
Here are Vitacost's Gluten-Free Categories:
They carry the flours in my main mix as well as most of the flours in my bread mix. Lately they've been cheaper than Amazon for the flours. And be careful they carry both Sweet White Rice Flour and Sweet White Sorghum Flour. My mix uses the Sweet White Rice Flour