The 6+ hour drive stings a little. That trip is every bit of 6 hours and then some. Add your price of gas to the cost of the tent too... it's almost 750 miles there and back.
Snow on Vail pass?.....you could add some significant time. Gotta figure 14-17 hours total by the time you drive out there, take a look at it, chat with the guy, mount it up. That really adds to it.
Now, if he'll sell it for $500 and meet you in GJ, you got a deal. Otherwise they come up for sale ALL the time.