Expert Foods makes the "ThickenThin" products, you can check out their website for product descriptions. However, I don't have personal experience to know the difference between them. I have xantham gum and use it for thickening. I bought it at my health food store for $7.50 for an 8 oz. pkg.

http://www.expertfoods.com/products.php#thickenthin

They also have some great recipes (I'm going to make their green bean casserole and sweet not/tatoes for Thanksgiving dinner).