I guess it depends on whether you were eating ramen noodles before. I find that I can keep most of my meals around $3 which is about $15 a day (add a couple of bucks for my post-workout shake). If you think about it, you can spend $15 on one meal if you eat out. Most quality lean proteins seem to cost about the same (albacore tuna in a can, chicken breast, etc). I never eat the cheap stuff (low-quality tuna in a can for instance), as I feel the protein quality is probably better with the more expensive stuff.
As far as supplements are concerned, a cannister of protein is going to last a while if you are just have one post-workout shake a day.
For me, I get the most satisfaction and results out of a diet that consists of quality foods; I guess I’m willing to give up some other stuff to make sure my food intake is the best I can make it.