Save on Ink, printing costs, maybe even make money

Here's my money saving idea for today.
Staples stores offer a $3 reward for returning used ink cartridges for recycling. You can bring in any brand, up to 10 per month. (That's $30)
Staples is 20 minutes away, but we were near there for something else today, and so dropped off our cartridges. I didn't need anything so I have credit on my rewards account, which I will use the next time I am over there and need an item. Packaging tape is usually cheapest there when we buy it in large quantities.
They do this in hopes that you will put $3 towards a purchase of a $50 ink cartridge, but you can use it for whatever you want. I don't use it for anything that I wouldn't normally buy there.
Here's how we use it to our advantage. We have been able to get ink cartridges (new) on Ebay for around $3 to $4 each. We've also found them at resale shops for even less. Because we are constantly printing pages for a variety of reasons, we go through a lot of ink. We can now take up to 10 of these cartridges in for a $3 return, making our ink costs nearly free.

The author, Corinne Johnson is a Christian homeschooling mom to six, a help meet to her husband Don, and the author of Vacation Education Books. www.vacationeducationbooks.net