You Run Barter Town

 is an achievement in Fallout: New Vegas which is awarded for successfully selling 10,000 caps worth of goods. An easy way to do this is to steal a bunch of weapons from the Silver Rushenergy weapons store (which are EXTREMLEY valuable), go to a merchant, save before selling the weapons, sell them and then reaload.

Behind the scenes
The title of the achievement is a reference to the plot of Mad Max Beyond Thunderdome.