How to get from Denver to Vegas on the cheap

Well, first, play this song:

https://m.youtube.com/watch?v=9WWHdBuOC6Q

Not going back to Denver?  I think one way rentals cost more...

I'm trying to remember, but I think my wife and I rented a dodge caravan for two weeks, drove stuff to my daughter in Chicago, then across the plains, Yellowstone, Utah, and back to Arizona. 

We took turns sleeping in the back on long days.  With some padding or an air mattress you could probably get away with it overnight, but two weeks of that might wear on you.   Motel 6 for an occasional break. 

We flew to Salt Lake City and drove a rental car for 7-10 days, in the early 2010s. Hardly missed visiting any National Parks, driving in a big circle. Managed to find a few hostels to stay at, including The Tetons, Moab, and a "doube-wide" in Cody, WY.

As for insurance, check with your current provider. 

State Farm covers any new/used vehicle purchase under your existing policy for either 10 or 15 days. So depending on how long you have the vehicle and your carrier, you could theoretically not even need to buy a new policy.

Let's say you have two weeks, how much of that time you want to spend both finding a car and selling it at the other end? It sounds to me like you don't live in or around Denver, right?

Also, if the plates don't stay on the car in CO, you'll probably have to insure and register it and wait for the title before selling the car at the other end. All that without it costing you less than a grand. Or, let's say the plates stay on the car, you insurance covers it without the extra policy, how easily are you going to be able to sell a car at the other end that's not titled or registered in your name?

If you want to do a car buying trip with a few side trips to national parks that's one thing but it sounds to me like you're trying to do it the other way around and the other half isn't on board. That sounds like a recipe for something that'll produce nice mushroom clouds on the horizon.

Honestly to me this sounds like you're trying to trade money for time, but potentially are setting yourself up for losing both. Not sure if that would be worth it to me. If OTOH there was a car in Denver or Vegas that you'd like to take home after the trip, well, that's going to change things a bit.

Plates don't stay on the car here in Colorado, they stay with the previous owner.  That means at least a trip to the DMV, paying taxes, getting a title (which most of the time they can print out right then) and getting plates.

One way car rentals can be expensive.  Some companies are better at it than other companies.  Enterprise is terrible at it, if they do it at all.  I highly recommend shopping around for rates with all the companies.  

Also, try to run the pricing w/o picking the car up at an airport or other tourist area like train station.  As an example, Hertz has cars at the airports but they also have cars in the Neighborhood.  These are the locations (like Enterprise is famous for) that are often located near the local strip of car dealerships and body shops.  These local shops have different rates and more importantly, the cities put different fees and taxes.  Cities usual add a lot of "tourist taxes" to the cars rented from or returned to airports.  These taxes and fees can be as much as $20 per day.  

Another option, how much would it cost to rent, one-way,  the smallest Uhaul or better yet Penskie or Budget truck for the same trip?  The van or 10ft box on a van body would be great for "camping' within.    Expect poor fuel economy.  

John Welsh said:

Another option, how much would it cost to rent, one-way,  the smallest Uhaul or better yet Penskie or Budget truck for the same trip?  The van or 10ft box on a van body would be great for "camping' within.    Expect poor fuel economy.  

My wife did that when she was younger. Too young to rent a car so she and two friends rented one $19.99/day unlimited mileage U-Haul after another. Hot, uncomfortable, slow and (IIRC) you could only rent for one day at a time.

I'd start with the car rental agencies. I once flew from Ottawa to Vegas, drove from Vegas to Denver and flew from Denver to Ottawa for less than the price of an Ottawa-Vegas-Ottawa flight. Weird.