Factory overruns are goods supposedly manufactured in excess of the original order. Be very careful buying any brand-name products promoted as 'factory overruns'. If the items were not produced within the order specifications, they are technically unauthorized, and anyone reselling them online can have their listings removed for trademark infringement.
There are penalties for importing and/or reselling unauthorized items. Some of these penalties are severe. You may have your marketplace account closed down, or you could be prosecuted.