Book wholesalers stock your book, process bookstores (including Amazon) and libraries orders to buy your books and ship the books. In return, they ask for a 55% discount.They don’t do any marketing for you.
Tip #1: When contacting Book Wholesalers, keep in mind that they won’t stock your book unless it is in high demand; for lower volume titles they will list it in their database and only order from the publisher or distributor as necessary to fulfill orders.
Tip #2: If you want to sell to retail bookstores or libraries, it's best to have your book available through Ingram or Baker & Taylor - the largest book wholesalers in the U.S.
Tip #3: There are a few ways in which you can get your book to be listed with Ingram. One is to print the book through Lightning Source, one of the largest POD printer in the U.S, owned by Ingram.