Hard to know what to suggest if we don't know what you have on hand and what you normally eat.
Since it is only a few days and you are trying to stick with a budget, you could think less traditionally for each meal (breakfast for dinner, grilled cheese for breakfast, etc)...and if you don't have a stove and are planning on cooking over an open flame, I'll tell you now that it takes some practice. I second the idea of the crockpot if you have electricity!
Pancakes, baked beans and toast, cold cereal (or even instant hot cereal) and fruit, yogurt parfaits, hamburgers/veggie burgers, chili and cornbread, foil packets of chicken/veggies/potatoes....all stuff I would normally have on hand and reasonably healthy enough, at least for a few days.
If you aren't well supplied with camping gear you may want to borrow from friends...outfitting a family to tent camp can be pricey to start! But you can make -do with bedrolls if you don't have sleeping bags...plastic plates or Corelleware (not too breakable) can be picked up cheaply at a thrift store and reused (better for your wallet and the environment)...one plate/cup/bowl per person is all you really need (plus flatware from home). Instead of flimsy foil pans I bought pots and pans from the thrift store....I don't care if they get black on the outside from smoke and if I ruin them I can toss them.....plus at about $1.00 each they were only marginally more expensive than a foil roasting pan! Just be careful that the handles aren't plastic or you could melt them!
Good luck and have fun creating memories with your kiddos! ..........P