Hundreds of Xboxs have appeared on online marketplaces such as eBay and Craigslist in the wake of the mass Xbox live bans.
Over the past week Microsoft has banned nearly one million users from the online gaming service after finding that they had modified their consoles to play pirated games.
Since the ban is connected to the console rather than a gamer's online account, many modified Xboxs have appeared online being sold by banned users.
eBay has issued a warning to users on its website to be wary of buying consoles in the wake of Microsoft's move.
In a post on the website's guide section, it said: 'If you are looking to buy an Xbox 360 on eBay in the near future, ask the seller if it has been banned from Xbox Live and be sure to pay by PayPal in case they lie. If you do get a banned console, start a PayPal claim.'
Microsoft has said that all bans are permanent to the console and no affected units will be permitted back onto Xbox Live on any account.