Is there any way to find lost books if the post office probably auctioned them all off?

Shipped 18 boxes of books to New Mexico from Utah last August, and 3 boxes of books were lost in the mail. After filling out paperwork and detailed descriptions and forwarding them to the lost mail department in Atlanta, Georgia, and waiting 4 months, as well as trying to contact them directly, I decided to just put in a claim for the insurance after finally getting ahold of someone live, who said, "Oh, we wouldn't have anything from back in August." But because the books included irreplaceable high school yearbooks, I am thinking if they weren't recycled, isn't there a way to locate them somehow? What might be the best place(s) to advertise such a thing? Would a possible reward of $50 or $100 be enough of an incentive?