If you don’t mind investing a little money upfront and doing the work, you can make good money buying and selling books with
We now have an app for both Android and iPhones that lets you scan the barcode of books to learn what merchants will pay for them. You pick the company you want to sell to, click their website and then follow their directions. It’s easy and can pay very well. I wish I had known about this when my children were little!
This youtube video explains just how easy the process can be.