The short answer: because printer manufacturers can get away with charging you that much.  Without ink, your printer is just a big paperweight, and companies know it.  That is how they can afford to sell you a printer for under $100 – they are betting that most people will continue to invest in the ink cartridges to keep their printer working.

Third-party refilled or remanufactured ink cartridges may be a lower cost alternative, but some are messy to install or deliver inferior print quality.  You might not realize it, but printer ink is very complex and is difficult to replicate.  In fact, printer ink is a technological marvel – capable of remaining fluid at extremely high temperatures, and then drying instantly on paper after being shot through a tiny nozzle at a speed of roughly 30 miles per hour.  Good luck getting your ball-point pen to match those specs!

Of course, printer ink is less expensive if you buy a printer that matches your printing needs.  If you choose the correct printer (two cartridge, four cartridge, six cartridge, etc.) for your printing needs, you will end up spending less on ink.