As for a used one of these my Miller sales man advised me away from them unless they were still under warranty. According to him all inverter machines have a life span of 7 to 10 years before they start having issues that cost a lot to fix. If you knew whom the prior owner was and how the machine was cared for I wouldn't be concerned but unless I knew the history of the machine I haven't seen any used one that much less than what a new one cost. I would pay the price for a new one.