Fill me up !

Its that time again, one of my cartridges has run out causing the printer to stop.  It uses nine ink cartridges,  which includes two blacks, one for gloss and one for matt. Each cartridge contains 25.9ml of ink compared  with 17.0ml for the normal cartridge so they do last a fair time and it varies as to what I've been printing as to which one runs out first but I have notice that the "Yellow" seems to be used a lot !
It is a bank loan job to replace them all but I tend to do that when one goes to I then have a replacement ready when ever I need it.
As I only have to do this about every 9 months to a year its not to bad as I do use the printer a lot.   How much does this cost ?  £000  !!!!!!!!!!!