Choices, choices.
The bright blue-with-wooden-stocks "standard model" is a thing of beauty. Some people really like the silver-and-blue tu-tone, and there is some thought that it resists rust a little better.
If you're considering purchase of a working pistol, with some military flavor, I think the Mark III is the best deal. Plus, it comes with a very sturdy finish. I personally don't care for the thumb rest plastic stocks, unless they are modified. A couple of the military parts dealers offer the plain black Canadian service stocks, and they fit right in with the overall image of the Mk III. And, certainly, there are a lot of really nice aftermarket wooden panels for sale.
The P35 High Power is a superb pistol, and the Mk III is serviceable right out of the box. Good sights, acceptable trigger pull which may easily be improved.
In my part of the country, $500 is a good price.
Best of luck,
Johnny