Coconut oil is expansive but a little goes a looooooong way. I rarely use it for cooking, but I do use it on my skin and hair, as does my roomie, and we've been working on the same jar for something like 4 months now. Even cooking with it, not that much is needed.
I prefer to cook with local olive oil or kerrygold butter, anyway.
Don't bother with nuts, or nutbutters. These are luxury items no needed for healthy living and certainly an excess in a student's budget.
Focus on meet, veggies, and have some fruit as well. Eat some potatoes or white rice as someone else said - these are very affordable staples and will bulk up your meals. For a long time I didn't let myself have them, but I've come to find through experimentation that they do not cause me problems the way other grains/carbs do. YMMV.
Buy conventional meat if you need to. Lean ground beef, skinless chicken thighs and breasts, ground turkey, ground lamb <- all very affordable. Supplement with butter, which can also be affordable.
I love the numbers someone above gave for Sam's Club. I am seriously considering a club card for myself, either there or at Costco, even though buying in bulk intimidates me. The prices really can't be beat.