Car rental/leasing for three weeks in Las Vegas

Do you know of an inexpensive way to rent a car in Vegas for three weeks? We're going to drive to Phoenix and Newport Coast, CA over the three weeks. I get great rates with my company discount with National at about $40/night including all fees and taxes (that's what costs so much!) Totaling $854.01

Any creative ideas?

Car rental/leasing for three weeks in Las Vegas