RE: Fred Bear Instinct versus Martin Bengal
I kinda have the same issue. At age 55, I can still pull a 70 lb. bow back but can't shoot more than about four arrows without shoulder pain. I found a used Hoyt Pro Tec 50/60 (2005 model) for only $300. Got all the accessories (top of the line stuff) for another $200. You might go on archery talk classifieds and shop for a used bow in that same price range.
I also got my 14 year old son a Fred Bear Element a couple of months ago. It is a very nice bow and shootsreal smooth.