Similar to Staples, they offer rewards points for every qualifying cartridge, usually capped at 10 per month.

If you only have one or two empties and don't want to deal with shipping, big-box retailers offer "reward" points that act like store credit.

One of the oldest services (operating since 1984), they buy both used/empty and new/surplus cartridges from all major brands.

A major player that pays cash for empty inkjet cartridges. They provide a free shipping label once your "recycling cart" reaches a minimum value (usually around $15) and typically mail a check within 30 days of inspection.