When I stayed in Las Vegas almost 19 years ago now, I stayed in a Motel 6. I remember it was right next to the Tropicana, and it only cost $30 for a fairly plush double room for one night.
I remember so well because the next day, at the all you can eat lunch buffet at the Tropicana for $2.99, I put $1 in a slot machine and it payed for the room plus some change!
I just did a check on the internet, and the same motel next to the Tropicana is doing rooms for about $46 a night.
If you do fly drive deals though, you may find that the accommodation is thrown in free at some of the larger hotels.
Incidently, I have also stayed at Circus Circus in Reno Nevada more recently. (about 8 years ago) The room was very fairly priced, pretty similar to a Motel room, but with lots more luxuries like computer games, and really expensive in room bars.