I have a 10 year old b&w Laser. It is USB only, so I looked at newer machines. I can get a machine with Ethernet, WiFi, NFC (and USB), duplex and a larger toner cartridge for 50% more than a toner for the old printer.
I ordered one and some toner for the colour laser. They phoned be up and suggested it would be better to buy a brand new colour laser (with WiFi and AirPrint) and duplex, because it came with 6k page toner cartridges. Throw in an 8k page black cartridge and the total package was £300 cheaper than the toner.
Now, I understand that the toner cartridges have to be sent back to the manufacturer, and that incurs a bit of a cost. Also that machines are now cheaper than they were5 years ago. But how on earth can a brand new printer with a full set of toner and an extra black one can be half the price of 4 toner cartridges for an older printer?