Recently started this book selling business and I need insight/advice from serious minded entrepreneurs.

We sell & supply books anywhere in Lagos. Our clients are pleased with the quality of our books, purchase convenience and delivery speed. We however intend to diversify for sustainability. We intend to introduce a "sell back" offer that affords our customers the opportunity to sell books that they purchased from us, back to us at a fairly lower price that is both fair to them and to us.

Do you think it is a good idea? A good but likely unprofitable idea? Or an idea worth giving time to?

Thanks.