CLA should not cost $300, more like $150-200.
Black paint, while it was the "budget" model when new (chrome cost more), is now collectible priced. Chrome will cost a lot less.
Also, black paint is much more common on a II than a III. If you want black on a budget, get a II. Only downside of II over the III is that the rangefinder magnification is 1X, which is less accurate than the 1.5X magnifaction on all the III models. Really only matters if you're using a Summarit 50/1.5, Summarex 85/1.8, or Summicron 90/2.
But realize that anything before a IIIa only has a top shutter speed of 1/500. With many Leica lenses only stopping down to f/12.5, you can wind up over-exposing in bright sun.
But the only way to get a IIIa in black is get an earlier black camera that Leica upgraded to IIIa. Thus, silly rare.