HP printer cartridges

Cost to make one black printer cartridge: About $4 to $5

Price you pay: $13 to $50 (depending on your printer)

Electronics manufacturers like HP are able to sell you inexpensive printers (which they make little profit from), because they know you will pay a premium for ink. In a Computer World story from 2010, HP also argued that it spends a billion dollars each year on ink research and development.