The generic ones are plastic and run around $100-$150. A correct fiberglass reproduction is around $400-$500. I think the 71 wing was a different style than the generic one but it would work if your not worried about originality.
The cheap ones seem to be good quality but you will want to strip the metal mounting parts and put a better coat of paint on them. I would also use stainless screws where they attach to the wing because the el-cheapos rust fairly quick.