…by selling things back to Amazon.
It used to be I’d lug the books we no longer wanted up to Madison to see what Half Price Books would offer me. Now an hour or so work online by entering in ISBNs and I’ve made around $60. Amazon pays for shipping (and return shipping if the item does not meet their quality standards) and I just have to arrange for packaging.
Amazon then goes through my order once it’s received on their end before crediting my Amazon account directly with the money. I’ll turn that around into books for homeschooling. It’s like recycling…but better! :0)