Gridmarket and Buddypress

My goal is to create a WPMU similar in nature to the ETSY marketplace. I have a testing setup with Gridmarket as the Main blog if you will it will globally pull and show all products.

I do not conceptually understand how or what theme I should use for the child themes in my design. Specifically it seems like gridmarket does not really feel like a buddypress theme to me.

Are there any examples of a Gridmarket/buddypress setup out there??? I really want to see how buddypress can integrate with a gridmarket frontend if that makes sense.