Regarding JohninKansas point about some colour being used in black printing, my Epson C60 driver has an option which allows this to be turned off for a particular print job, thereby saving the coloured ink. It is well worth checking in other models.

Also note that the chipped Epson cartridges usually signal that they are empty with up to a third of the ink remaining. A chip zapper gets you access to that otherwise wasted ink. It also allows those cartrides to be refilled, although I have not tried refilling any yet.

Richard