The Model 13 is built on the K frame. It is not a 'big' revolver. It was cataloged as the 357 Magnum Military and Police, Heavy Barrel. No bigger than a Model 10.
$312 is just an OK price? Not around these parts.
I picked up this Model 13-2 a few years ago. You can see part of the name on the papers that came with this one. I seem to remember it was somewhere around $500. Can't be absolutely sure. But it sure as heck was not $312. This one shipped in 1979.
Gotta say, I hope all this media attention has not driven the price up.