If you are looking to have this gun but dont really feel like paying for it. You can find one on a dead guy at Cottonwood Crater. I dont know about ammo though. I still havent found any mini nukes.

The only one I have came across is the one in the southern lake of the quarry where all the deathclaws are. There was also a mnuke in the deathclaw nest north of the pond. I'll have to check the crater out.

P.S. I am going to be pissed if there are only a couple of mininukes for this thing.