My daughter has been gluten free for about two years. Talk about an adjustment!!
Betty Crocker has gluten free brownies, cake mixes and cookies. They are around $5 a box, but they are absolutely the closest to "regular" food. Betty Crocker also has a rice flour blend which is very good.
Also, forget all the GF pastas that you buy in the health food stores or Whole Foods. Not only are they incredibly expensive, but they are AWFUL!! Muellers pasta now makes GF fusilli, spaghetti and rotelli. Each box contains 8 oz and is $1.59. More expensive than Non-GF, but tastes wonderful and the consistency/texture is wonderful. And MUCH LESS expensive than GF pasta you buy at Whole Foods or health food stores.
Try Betty Crocker GF mixes. You will be pleasantly surprised!!