its a nearly impossible question to answer, different manufacturers put different amounts of ink in their cartridges, use different amounts while printing, use different amounts for print head maintenance. They often have "page yield" ratings, like a cartridge can be expected to last "500 prints" but each manufacturer may use a different print to test this. And its continuous printing not including maintenance cycles. Then there is tri-colour cartridges, vs separate colour inks, and printers with more than 3 colour inks. I would say stick to a printer with 3 separate colour cartridges, there are some that use between 6 and 8 cartridges and will be expensive. If you want something really cheap to run, get a laser printer.