I pride myself on not paying more than I have to for things. In real estate one of the things you can't get away from is using a lot of ink. But I have a system in place that allows me to pay about $1.25 per cartridge.
First get an ebates account at www.ebates.com
Then search on the ebates website for ink and a company called www.123inkjets.comwill come up. If you click the link through ebates then you get 16% cash back on your purchase (once a quarter ebates will mail you a check) and you will also see all the current coupons 123inkjets has going. Right now they are offering 15% off plus free shipping on their 100% compatible ink cartridges. I have been using their compatible cartridges for about a year now with no problems so you don't need to buy name brand. I am ordering 3 black cartridges at $3.99 and 4 color cartridges at $4.99. Subtracting the 15% discount I am averaging about $3.87 per cartridge and then if you count my 16% cash back I am earning through ebates I am only paying $3.25 per cartridge.
Lastly Staples will take up to 10 cartridges per month and give you $2 credit for each cartridge in the form of a rewards check you can use in the store or on Staples.com. I then use the rewards check for things I would have purchased anyways. If you don't have a Staples rewards card you can sign up in the store or on www.staplesrewardscenter.com This brings the total I pay for my ink to about $1.25 per cartridge. I also just found out that Office Depot has a similar program called Worklife Rewards and supposedly will pay $3 for any ink cartridge up to 20 cartridges per month and the rewards don't expire for a year but I haven't personally tried taking any in to them yet so I can't say from personal experience. If it is true though I would basically only be paying .25 per cartridge. You can enroll at www.myworkliferewards.com definitely check the terms though as it looks like they will only give you rewards up to the amount you spend there.
Hopes this helps you have a little more cash to enjoy life!