After viewing this video on foods you can eat a lot of and not gain weight, I took into consideration the costs of the food.
Healthy foods always get a bad rap. However, if you do your research, you CAN afford them. The video had 22 suggestions. Many were quite costly. So, I am going to share with you what I think are affordable...
Eggs
Cucumber
Salads
Boiled potatoes
Broccoli
Cauliflower
Oatmeal
Broth-based soups
Cottage cheese
So, pay attention to your local grocery store's sales. Although, even if not on sale, the groceries I have selected are still going to be cheap. Study some new recipes so you do not get bored.
Good luck!