10k for the ventilator is on the low side, but assuming you could buy one you still need an ICU or rough equivalent to take care of everything else and a massive autoclave for periodic sterilization or you're going to get a nice infection on top of your already very bad air supply situation. This is well outside of DIY territory, though there are people living in 'Iron lungs' for decades (but those are typically strong enough to survive for a while outside of them and can breathe independently if they have to, they use the iron lungs for relief).