HP ink wastage - Not an economical printer

We have 2 x HP OfficeJet Pro 9023's, but one of them we strictly print in black. Yet I have to buy a full set of colour cartridges in order to use this printer even though the default printing is set as Black only. We now got clever and when I try to print in Black and it says I can not continue untill I refill the Yellow / Magenta / Cyan, I take the used cartridge from the other machine and give the colour machine the full colour cartridge. Yet, twice in a row now the black printer starts with replace one colour, so I do and then it immediately says replace the next without having printed even one page! And guess what after I replaced that one it asked for the next - again without even printing one page! It did not even warn yet that, that colour was running low. To add insult to injury, the Yellow was low on the colour machine, but not yet warning that it was low, but putting it in the black machine it said it was depleted. It costs over R3,000 to buy a full set of XL cartridges and HP wastes a lot of ink with printer maintenance it seems - it didn't print any pages, but after the maintenance is done when inserting a cartridge, the ink is suddenly gone! I have photos as proof. I really feel HP should work on ink sensors at the price they charge for original ink. I would not recommend anyone to buy an HP printer if you predominantly print in black. I know it uses a bit of ink to keep the printhead from drying out, but I often insert a ½ full colour cartridge (that I never use), yet it is up within a month or three. That is not fair usage and costs a fortune! Not happy - I don't see any reason to continue buying original ink at the cost and waste of HP technology. HP you should be doing better in this technological advanced age.