Another unusual side-effect of expensive printer ink is that you'll replace your printer with the same brand just to use your spare ink. That is, if your printer lasts a while, and you have some spare ink left over when it does break, it may be more worthwhile buying the same brand of printer rather than letting that spare ink go to waste.
Mokalus of Borg
PS - It would depend on how much you spend on ink over the lifetime of a printer.
PPS - Or how much you think you spend.