I suggest that you look for sales in the local ads for the office supply stores (office max, office depot, walmart, staples, best buy, circuit city) These stores have ads such as “buy one get one 50% off” or “Buy one and get a $10 gift card” or “buy one and get this FREE Flash Drive or Memory Card”. These are the kind of deals to look for!
Also if your Ink cartridge size come in XL or what is called a High Usage size GET IT! It may seem like it costs a lot upfront but these High Usage cartridges last longer and save you money in the long run. A normal cartridge will print about 150-200 pages. A High Usage cartridge lasts for about 400-450 pages. Check your Printer/Ink Manufacturer website for more details.
You can recycle your used up cartridge by taking it to Walgreens/CVS/Office Max for a professional refill. This is a cheap and effective way to get the most ink for your money.
If the store does not support your cartridge or it is too damaged to be refilled, take it to Office Max. They will give you $3 off for every used cartridge you recycle to them.