I'm sorry you're in that situation... I can't believe how much groceries have gone up its crazy!!
Before I moved in with my boyfriend me and my brother (roommate) would get snack stuff and some regular foods at big lots for pretty cheap. I would just be careful to get stuff that is securely sealed bugs cannot get into because im sure that stuff sits in warehouses for long periods.
We don't have these in Vegas but in Cali we had 'grocery outlet' stores, they were super cheap most were off brands but sometimes there was non generic stuff.
Oh and the dollar store, dollar tree, or 99 cent only stores have snacks at the very least.. just check the expiration dates!