I've seen a lot of plow trucks, and there's a couple of things you need to know. If it was used as a dedicated plow truck, it will have twice as many miles on it as the odometer says. The other thing, is that if it was used a lot as a plow truck, the frame could be tweaked. It really depends on how much it was used to plow. If it plowed a farmers driveway and that's it, it probably isn't in too bad of shape. If it plowed 50 driveways every time it snowed, it might be best to walk away. If the frame is good and it runs, the price is really good. Buy it, sell the plow for a few hundred bucks, and start your rebuild.
I'm not sure what tomorrow will bring, but it can't be any worse than what I've already been through.