They are so rare I only had 4 by the time I finished the main quest, surely there should be more to collect? In F3 they were quite rare but in FNV they seem like gold dust The Fatman was one of the best guns if fallout, it feels kinda pointless to even carry one in NV..................

Get GRA, and you've got unlimited mini-nukes. But without it, they are much rarer than FO3.

You can stealth kill Boomers and loot them every 3 days or so. Make sure you don't kill anyone important!

Alternatively, you could just get GRA, which does supply more Mini Nukes, plus more types of them as well.

I just got the ultimate edition, how do I get the unlimited nukes?

Boomers are my friends.......

Well, when you visit merchants, all their stuff has GRA tags on them. Visit the Gun Runners and they are the biggest group affected by GRA. They sell mini nukes and most variants. I saw Chet or somebody offer one once.

Various merchants sell them, and their stock respawns once or twice a week. However, I think they only sell GRA variants (bigger blast, smaller blast, and timed). If you want unlimited regular mini-nukes, you have to kill Boomers.