Here's how I manage gluten free on a budget:
1. Mostly eat naturally gluten free foods. Fruits, veggies, dairy, rice, meat, and nuts. For "sandwiches" I either make lettuce wraps for gloopy fillings like tuna salad or chicken salad (they are fun! you get to roll them!), use corn thins (~$3 for 26 "slices") for things like lunch meat or peanut butter, or make corn tortillas.
Making corn tortillas is easy - our
Walmart carries Maseca corn flour 4+ pounds for ~$3. You mix 2 cups corn flour with 1.25 cups water and a dash of salt, roll or press them (I bought my tortilla press for less than $10 from the local Mexican foods market -- they also carry tapioca flour cheap), and cook them on a griddle or in a pan for a couple minutes on each side. You can also use them to make tostadas, enchiladas, taquitos, taco shells, quesidillas/grilled cheese -- and you can use the corn flour to even make ice cream cones and fortune cookies (check the Maseca site for recipes).
The premade tortillas you buy in the store just can't compare (and the Mission brand ones make me sick since they moved to a shared facility, anyway.)
I've yet to find or make a pizza crust that I find satisfying (Chebe is the closest, but it's $6 for 2 crusts, so I skip it), so I just use corn tortillas often as not for pizzas, too.
For brown rice, I mostly buy Steamfresh. It's more expensive than a bag of brown rice, but I've just never gotten a handle on cooking it.
2. For gluten free specialty items, I mostly only buy pasta and Pamela's baking mix, and that mostly from
Amazon using Subscribe & Save, except cookies or something as a special treat. The easiest gluten free breads are quick breads -- pancakes, pumpkin bread, and banana bread I've made taste pretty close to gluten versions, and I think the pumpkin bread is even better. Check the Pamela's site for recipes. Also, you might need xanthan gum occasionally. I buy that from the bulk spice section of my local health food store and just a small amount lasts ages. Also, sometimes, I will buy the Glutino cheese crackers to use as a coating to make baked mozzarella cheese sticks. Pamela's + spices works for fried chicken/onion rings/other "deep fried" (I generally coat and bake) treats, but the cheese sticks need the crackers, IMO.
3. The Gluten Free on a Shoestring blog has some good recipes.
4. If you can, buy fresh spices from a local farmer's market or spice shop (or grow them). They make a world of difference.
Good luck!