I did a from-the-ground-up rebuild (including the engine) just after buying it. That cost an arm and a leg but all in (including the original car) it still came to ~half of what a new one would cost. Anything that had been 'improved' on it was brought back to stock. It's been super reliable, I've had it since jan 2020, put a considerable number of kms on it and it hasn't let me down (so far :) ).

As for doing the maintenance myself, I don't have experience with this kind of car at all, I've worked a lot on classic Mini's, Citroens (2CV and DS) and Austin Maxi. But never anything like this so I'm more than happy to let someone else earn a buck on it. But it's been pretty cheap to run so far, fuel, oil, regular service and once a control arm that got bent out of shape.

Compared to a new vehicle I'm considerably better off.