Seems like Facebook would be best positioned to do this. They already more transparency than Ebay/Amazon with regards to who you're dealing with. They also have

Seems like Facebook would be best positioned to do this. They already more transparency than Ebay/Amazon with regards to who you're dealing with. They also have regional buy/sell groups already. Integrate with some shipping platforms and they'd be on their way. That being said, its not really in their lane.