Hi...
While addressing to your requirements i have observed that this project can be completed by following the below steps:
1. The project need "Users Authentication System" to login from facebook as well as the website own user management system to make/ create accounts.
2. A completed personal dashboard, where a user can make his own settings for his interest related items. In other words, The user will have his own details regarding his all activities on our website (his own search history, recommended items for him, his buying (cart) & selling details, his balance (payments & receiving, invoice making script, credit details etc.)
3. User must be able to use your website's platform as an online web store.
4. User must have option to post goods available for sale in his own store/ online shop.
5. Custom filter search engine for his interest related items on location base mechanism.
I have team of members to work on this project immediately. Looking forward to discuss.