Hi Guys,
I am thinking of building (or have it build) a social networking site with the possibility of back end management just like CMS, so administrator of site can add/modify things on the sites etc.
Plus I am also looking for plugin/widget container inside it, so developers/enthusiasts can add plugin or widget on the
site for free or can make money.

What technology you suggest can help it develop in quick time, I need a honest opinion and what can it cost me if
I want it to be build, any suggestions?