I don't agree. Sounds like the right interested party could get the collection for just the cost of shipping, which seems reasonable to me.
But I’m reacting more to his certainty that he will have so many people wanting to pay for his books, that he’ll actually be trying to decide whether this or that library will have the privilege (and that he’s being magnanimous by not charging for it). Again, he really doesn’t understand the book market.
It would have been wiser to ask a local bookseller to take a look (and tell him the brutal truth) before posting his “offer.”