Buy color toner refill kits. Melt a hole in the cartridge with a soldering iron, refill it, and seal it with aluminum tape.

Better to spend $70-150 than $300-1200 on new cartridges.

PS: I'm currently in the market for an 5-15 year old HP Color LaserJet but still assessing which model tends to be more reliable. There were a lot of lemon SMB Color LaserJet models. Suggestions welcomed especially by staff IT people who support these things.