Inkjet printers are sophisticated technological devices that are typically sold at or below cost.  On the other hand, ink for that bargain printer is downright expensive. That 2 ½ teaspoon cartridge of black ink for your HP inkjet printer priced at S17.89 extrapolates to $4797.00 per gallon. If you typically print only a few pages a week, more than half of that pricey ink may be consumed by print head cleaning and other maintenance cycles.