I've been wanting to go to this "museum" for years. The unusual hours and the high cost kept me away on several Vegas visit. I finally went and visited for a morning tour. It's $18 ($12 student) for an hour tour.
Seeing all of these signs up close is really neat, and it's a great spot to get some really cool photos. Still, the hour tour provided a lot of info that I didn't really care about, and the place would be much better suited if the was an audio guide and/or some signage describing the pieces.
I'm glad we did the day tour. It can get quite hot for the last tour (10am in summer), but the night tour at the time only had 4 signs lit up and cost $7 more.
Free parking on site.
Bottom Line: Cool, but overpriced. Good tour, but this space could be much better and cheaply operated.