We got ours at Bradis. They used to have a bunch in the case, but that case is now full of P38s. There's still probably a couple of Nagants around. Give them a call to be sure though before heading in that direction.
They're about $100 online, I would pay more than $140, you'll need the money for the ammo.
Remember to hold it and yell, "One man gets the rifle, the next man gets some bullets. The second man follows the man with the rifle, and when he is shot, picks up the rifle and carries on fighting!"