I heard 3d printers are quite cheap on the used market, so maybe its worth a look for you.

I thought that I would constantly need an AMS, but it turns out for me at least it is just not needed... You could always design your prints in a way where you just manually change the filament on a specific layer (set in the slicer) and print with the other filament that way. Sure an AMS can do much more, the question is how often would you need that capability.