I was lucky, I bought a very nice condition 1969 M4 for 500 Euros ($650) from ebay (German seller), not mint but in very nice Exc+ condition, I have checked the shutter and the speeds are accurate and the first 2 films through it showed nice spacing, rangefinder seems to be reasonably accurate with my lenses and the exposures were as would be expected.

My intention was to buy at that sort of figure and allow for a CLA, at the moment I am just happy to be using the camera and will arrange for a CLA later.