I won't debate the statement that $700 is a bit high. But here are a few things to consider.
1. That one is not one of a "zillion." It is one of about 180,000 that were assembled in the immediate postwar period (1946-1948). It will have an S prefix serial number under about S990000 and above about S813000.
2. It is wearing original stocks of a style that were only made from 1946 until 1952.
3. It has the 6" barrel, which was the length least installed in the postwar M&Ps from 1946-48. The order from most to least was 4", 5", 2" and 6".
4. A few short years ago, you could have bought that gun for around $400. Now many of them are selling for around $600, even with a bit of muzzle wear like the one in your picture. Five years ago, I was buying them like that one with the original stocks, original box and HH for $600, and $400 for one without the box.
If you want just any old M&P from before model numbering, sure, you can hold off for one in the $400 to $500 range. And you will find one. But for one from that particular period with original stocks and 95% original finish, $600 isn't bad at all considering today's prices.
You just have to decide what you want and what you can afford.