Theo wrote:

Obviously toner is the mainline drug they're pushing, but it's almost worth
buying a second printer to store unopened

Almost?

in order to have a stash of drums, fusers, etc that you can swap into
the other one for less than the price of official spares.
In the case of the cs317dn ...

one printer with starter toners
1400K/750CMY pages = £58

one printer with starter toners plus a set of full toners
4400K/3050CMY pages = £324

five printers with starter toners
7000K/3750CMY = £291

And that's before you consider drums/fusers/waste bottles further down
the line.