I want to set-up a multi site environment where I can

I want to set-up a multi site environment where I can provide e-comm website tools.

Marketplace looks like it will work in multisite.
I don't want to set up an etsy type website. I want each site to appear stand alone and have a unique url.

I read that I can take a commission on each sale, this is what I want to do.

How exactly will this work? Does it work with any of the payment gateways you support?