"Cost effective range" and Vegas is an oxymoron. Full auto isn't cheap anywhere.
Never been to this place, but I have seen the Humvees picking up customers, and heard it was fun:
https://www.battlefieldvegas.com/
They have packages set up where you go through 4 or 5 or 6 guns according to a theme. I think they will also do outdoor shoots, which would be infinitely more fun than indoors, but that's more suited to groups because it will be much more expensive.
They even have a mini-gun that costs $200 for 100 rounds. It fires ~4000 rounds a minute, so you can do the math on how much fun per second it costs.
Whatever you choose, budget for about twice that amount because once you fire a magazine, you'll want to do another one, or two, or three. It's like crack. Well, I've never used crack, but I do have friends with machine guns and I would imagine it's similarly addictive.