Trader Joe's sells almond meal pretty inexpensive. Just look for it to contain 1 ingredient: Almonds. They also have ground hazelnut meal too.

Flaxseed meal is another useful thing to have on hand.

I stopped using soy flour after getting concerned about eating too much soy and its estrogenic properties.

Another thing I like is to have flavourings: lemon, almond, maple, banana are good ones.

I've made low-carb waffles, they're great!

Oh yes, another ingredient if you'll be baking is Wheat gluten.

I think concentrated splenda liquid is very useful for keeping carb counts down. Doesn't have the carbolific filler that regular splenda does.

I tried to make a low carb sponge cake. Boy.. that experiment was a total failure!