Multisite limit on who can create a new site

I'm looking for a plugin that will allow me (the superadmin) to control who can create a "site" and who can create a normal account.

In my network there'll be basically 2 classes of visitors. It'll "businesses" and "clients"

I don't want the "clients" to be able to create new sites. The way I see it this can be done in 2 ways.

Either I approach it like membership site ex: silver members are regular members, gold members can make new sites.

Or anytime someone tries to create a site I have approve it. I'll want to approve all sub sites anyhow.

Any plugin ideas that can help achieve this?