If your budget is $2.50 per day for food then you are probably looking for much cheaper options for a refrigerator. I understand it's possible to buy small chest freezers and convert them to run at fridge temperatures and they're very efficient that way.
Of course, if you were trying to save money, you would get a chest-style fridge where all of the cold air doesn't fall out every time you open the door.
If your budget is $2.50 per day for food (or $3.30 adjusted for inflation) that's significant.