KnightBrolaire
SSO's unofficial pickup tester
I'm mainly quoting this so it isn't buried. The other discussion is also important and I think still on topic but this is more directly on topic.
Beans are great and easy food. Don't discount them if you think you don't like them, there are lots of different ones and you should be able to find some you can enjoy. The great thing about beans is although the preparation is long it isn't time consuming and they can and should be prepared in bulk and then frozen for quick easy eating. Soak them, cook them then freeze them and reheat as needed.
Peanut butter can be great at the end of a day when you haven't met your eating targets and don't feel like preparing food, it's an easy choice that helps you sleep if you have it on bread a couple of hours before bed.
I'm not sure how it is in the states but canned tuna is not really cheap over here, it seems cheap when you buy a can but when you work out the unit price you can better off financially buying wild caught frozen fish and cooking it yourself. It might be different over there.
canned tuna in the us is pretty cheap, though there is varying qualities (basically how many guatemalan children's fingers you want ground in with the meat, some or none). Canned fish can be had for anywhere from .50-1$ a can depending on the size of the can. Good albacore tuna costs like 2-3$ a can/bag. Frozen tuna is pretty pricy at around 7-10$ a pound iirc. Frozen chicken is like 2-3$ a pound. Basically it's the same here as there, buying frozen and in bulk is the cheapest (if you're dollar cost averaging) but for the OP's purpose canned goods are just fine.