Social commerce engine suggestion please

I'm looking for a social commerce engine to power my new commerce business. Not talking about the typical oscommerce (hack & slash) solution but a more complex & comprehensive solution that allows multiple businesses to run their stores on my marketplace, print shipping labels easily, and process credit cards (paid directly to the small businesses on my site minus my commission).

I've looked at shopify and bigcommerce, they don't quite do what I need. But still looking, if anyone has any suggestions please please post it.

Thanks!