Is this what I needed?

I apologize if I am asking too many questions. I really do research before I ask though :wink:. I just made the switch from a regular wp.org blog to wpmu w/ marketpress. I did this b/c I thought it is what I needed....now, I am not so sure. All I want is the capability of others to be able to set up shop in my site. Could I have accomplished this w regular wp.org? I do not desire to have other people blogging or accessing my admin...I just want them to be able to configure and open up a shop of their own on my sight, be able to collect a transaction fee....you know, like etsy or shopify (i like the look of shopify better). I am so confused. please, please help. thank you.