How much is a 3D printer that can print durable thermoplastics that I can use for replacement of trivial household items? I thought that would require an industrial setup to do. If you're telling me that I can just start replacing plastic crap in my house, including critical parts like plumbing, with a 3D printer that can sit in its own corner, I probably WILL buy a 3D printer.

A Bambu Lab P1S is $600, and then you gotta buy PET-CF filament, and there's shipping consider as well, so let's say ballpark $800 to start. They make more expensive printers too if you have the budget for it, but the underlying technology is mostly the same. Filament comes in 1kg rolls, and small stuff is like 50 grams, but a large piece of pipe including support structure could be as much as 500g, so if you end up printing a large amount of large items, eg https://makerworld.com/models/1441653 instead of https://makerworld.com/models/77668, which is 2g, and cheaper PLA, filament costs are going to add up.

https://bambulab.com/en-us/filament/collections/functional-p... goes through the various filaments and their different strengths and weakness, depending on the kitchen sink drain pipe you're printing.