For what it's worth-- I was tasked with selling off a deceased friend's shooting and reloading stuff recently. Much of it was/is new, and since he was a chemical engineer he kept all of it in excellent condition. I tried to price it at about 80% of new, and frankly had a difficult time selling much of it. Seems as if we're a cheap bunch, always looking for deals.
But if you offer 50% of new that should be a fair price.