actually frozen vegs are as nutritious as fresh - maybe more so, as they are frozen immediately, compared to the "fresh" in the store which has been sitting around, as you said.
I think you can eat pretty healthy and cheaply if you eliminate meat, soda, junk food, and most processed or convenience foods. I am amazed at what people pay for a little frozen meal, lean cusisine or such. And when I have a coupon for a free one, I open it up and DH says, where is the rest of it?