why low carb? because carbs are cheap and you dont have a problem buying them, or because you have bought into the low carb nonsense?
im also assuming you are looking for protein sources? if thats the case, believe it or not, whey powder actually works out to be cheaper than most real food sources. Check out the link in my sig. Whey concentrate in a bag from TP is $4-something per pound. Thats $4 for 450g protein. Thats fifteen 30g servings of protein, at less than $.30 per serving.....cheaper than tuna.
Also check out your local grocery sale ads. You can usually get decently-lean red meat for a very good price, they also run huge sales frequently on meat thats going bad soon. My roomate just $100-something of red meat for around $20 at Food Lion because it all expires tomorrow. Just freeze it and its good to go.
Eggs are dirt cheap.
If you want fat sources, peanuts are cheap, and so is olive oil and canola oil.
