I just learned that Las Vegas has instituted a new $3 a day surcharge on rental cars, similar to what Florida has had for quite some time. I had one reserved for the convention two months ago but when I called Avis today, they said you pay what is current, not what is on your reservation.

That said, here's a reference rate for an Avis compact that you might want to use for comparison if you are renting during the convention. I have a car for 9 days starting the Saturday before the convention with a rate of $215 including 50%(!) taxes, surcharges, fees, and kickbacks.