I don't of a cheep online feed source. But if you need to buy yourself some time you can feed the following.
Dry split peas, lentels, beans (cooked), Rice(cooked), Potatoes (cooked) Canned Fish (cheap), Meat scraps, Sunflower seeds (no shells), Finch seed mix(mostly millet). Bread Whole wheat (Day old),Old produce from grocery stores, yogurt(with live active cultures), Eggs (boiled and blended beyond recognition) have neighbors save their egg shells and blend with your eggs.
this is just an emergence list to give you some ideas of you can do and time till you find a balanced feed.
what ever you can get your hands on.
Good luck.