Depending on your needs... it may be worth buying a new printer.
I know, it's insane! And yet, inkjet inks are extremely costly. Take a look at the following graph, taken from
an entry in Gizmodo:
It's common knowledge that printer manufacturers make money not through their printers, but with their ink. Classic razor / razor blade business model.
If you want to go cheap, Brother makes perhaps the most cost-effective printers out there. For example, their monochrome laser printers cost less than any other laser printers and most inkjets! It is also capable of producing black and white prints that is almost 1/10th of what it would cost to do the on an HP inkjet!
Color laser printers are still kind of pricey though. For photo prints, I like Canons. I have a mid-range Pixma, and although it's an inkjet, prints per page is still typically lower than HP's AND all of their printers are built for individual ink tanks. No wasting ink like HP's consumer line.