Oh yeah, back to the food Q's.
As the lads have recommended, tuna is a definite option. Tuna is really cheap, yet contains 30g of protein per can. I know, cheap tuna sometimes tastes crappy, but put some vinegar, pepper and some oils (for dietary fat) on to improve the taste. Or you could put some mayonese in as well.
Again, yeah, eggs are cheap. Large eggs in Britain contain about 8g of protein per egg. Cottage cheese is also quite cheap. As is quark, which is a soft cheese product, and each tub contains about 30g of protein.
Also get some whey if you can find it cheap somewhere..
So now that you're getting your protein in from the sources above, you need your fuel and essential fatty acids. Cheap fruits are decent carbs, i.e. blue berries, apples. Oats are always cheap. You might have problem getting enough calories being broke, so get loads of fats down. Healthy and cheap oils are the fish oils (cod liver etc), flaxseed oil, sunflower oil etc. By taking your choice of oil(s) regularly, you'll find it easier to get enough calories - a tablespoon of oil contains about 120 calories
Being broke, I reckon you should forget about good supplements such as creatine and taurine..unless you find some for cheap or your mates are willing to lend you some
-shaun