In North America you can buy refill kits which are usually compatible with most printers (some printers use different inks, but if it is a standard HP printer should work) yeah unfortunatly HP printer cartridges have the heads on the cartridge. I know for cannon's and epsons you just have to peel back a sticker and inject the syringe (with whatever colour) in the cartrige. Lexmarks you have to drill a hole in a specifc spot on top ( I think HP is simillar) do a google search for your HP (+ series #) refill, should find some documentation on it. Yeah it is usually cheaper because you end up getting a few refills out of one bottle.