The price is fair with only one mag. The mags are getting harder to find. They are a fun gun to shoot once you get used to the 14 pound trigger. They were originally designed to be a 3 round burst pistol with the shoulder stock installed. The cyclic rate was 2200 rounds a minute. The idea was to get all 3 rounds out of the barrel before the recoil started to move the gun.
Depending on number of rounds fired, somewhere between 850 and a grand. Slide over to HKpro.com, you can look at the history of the gun, There may even be one for sale.