The joys of an inkjet printer, it's sometimes/usually cheaper to just buy a new printer than to replace the cartridges. You'd be better off looking into a laser printer, it'll work out cheaper in the long run and last a lot longer - maybe something like a Brother L2750 or a Canon MF743?
I thought Laserjet meant it was a laser ?
Any road, thanks for the recommendations, Canon seems like a good shout.