In printer ink cartridges the cost of ink averages out at about $1000 per litre, a bit over for colour, a bit under for black. Some manufacturers are dearer than others. The chips fitted by HP, Epson and others often show empty when there is still a third of the ink left.

Laser printer toner cartridges also suffer similar problems but usually work out cheaper per page. Sensors are also used to show low toner levels and in some makes stop the machine, one user claimed he got an additional 1.800 pages from a toner cartridge by blocking the sensor "window" with black tape.

Recommended price for manufacturers toner cartridges for my laser is about £65, unbranded refills £26, and that is for about 3500+ A4 pages, many ink cartridges do about 150 pages. Toner doesn't dry out if not used frequently unlike most inks.