I have been thinking about a system where you can donate your book into a pool for a credit valued at, say, 80% of the used retail value of the book. It would have to only be books that are still in print, and only books that are common across classes or even schools, like math and science textbooks.
You could use that credit to purchase other books you needed at 100% of that used retail price, and then choose to either return it or not. If I had the resources to do it I would really like to do it to help out students, but you have to account for the unpurchased books in your pool, how you deal with people's credit if you don't have what they need, and so on.
I think something like that could work, but you'd need the money to experiment, or make the percentage value of donating a book lower to compensate for inevitable losses. It'd probably still save students quite a bit of money, only losing like 20-30% of the value they bought it for. Even buying used and reselling you only get about 40-50% of what you bought it for back.
