Yes! Buy Empty Ink Cartridges Now!
I worked at Staples for years. When the "bring in an empty ink cartridge, get a $3 coupon" program started, we had a few people who brought in a TON of cartridges. Our district had to implement a policy, and I see it's now a company-wide thing - you can now only bring in so many cartridges.
Well now you can buy empty cartridges on Ebay specifically for taking to Staples.
This wold just never stops amazing me.
