Properly prepared Ramen noodles (add vegetables, an egg and maybe a little meat) will provide a filling and relatively healthy diet while allowing you to divert more funds towards military surplus firearms.
For anyone who does not have a K31, get it now! They are hands down the most accurate milsurp I have ever shot and can still be had for under $200. You can load your own ammo if you can't find the GP11 using .284 Winchester brass resized to 7.5mm.
I've got 2 K31s, both of which are relatively beaver chewed, and finish worn a bit, but mechanically perfect.