all these higher prices are caused by the assumption that Leica personnel was more skilled by the time the production run was coming to an end.
This has never been proven, by comparing an early batch and a late batch of cameras for the number of service returns. Although it sounds feasible, it is just as easy to have the opposite sound likely: by the end of the production run the Leica personnel got bored with building the same model over and over, thus performing a sloppy job on some examples. Furthermore, as time progressed the more skilled workers left the factory and were replaced with apprentices who still had to learn their masters' tricks.
I own two early double stroke models (734xxx and 804xxx) and both work like a clock. Both have dents and scratches, both get used almost every day.
Just get any Leica M3 that is in a trustworthy user condition and burn film. If you are planning to use it for the time we have left until film meets extinction, paying extra for a late model (and subsequently always being overly careful with it) will not make you enjoy the camera more.
If you are planning to buy for a collection, that's a whole new ball game.
Just my 2 cents. Hope it helps make a decision. Enjoy your Leica!