Your having to be 18 to legally sell on Amazon may mean you need supportive parents to get you started anyway, perhaps they can give you ride now and then. You probably need to be a bit selective in picking titles that will sell and getting decent quality books, really need to see them in person, that added shipping would eat your profits as well.
I have never bought a used book there, the profit potential, like in this guy's video may be over stated. Try testing it with as relatively small batch of quality books before shipping tons to Amazon, also learn about proper packaging of individual books.
https://www.youtube.com/watch?v=oh57z4Bp...
Looks like you want to get in the business of picking free books and selling on Amazon. Did you realize why the books are free? books are free when no one wants them. Selling books that no one wants will be frustrating.
50 boxes of books will be very expensive to ship.
no they arent going to pay to ship them to you.