Multiple sites project

I would like to have three different paid financial newsletter sites and also the corporate site that acts as the host for everything (purchase site membership or up sell to multiple newsletter site membership discount, newsletters, transactions with PayPal). Should I just start with the corporate site pointing to each individual site and each take care of their own membership/newsletters/transactions or do you have an idea of how to get to the corporate site taking care of those duties for all the sites?

Hi there. Thanks for your inquiry.

What you’re describing sounds like a task for WordPress/s2Member running in a Multisite Network configuration.
See: http://codex.wordpress.org/Create_A_Network

On a Multisite Network installation, s2Member runs as a separate instance for each Child Blog that it’s activated on. So to answer your question… you can have a Main Site, and you can also have Child Blogs (aka: sub-sites). Each of these sites will run with a separate instance of s2Member.

It’s not possible to run s2Member on a Main Site and have all configuration on the Main Site automatically trickle down into sub-sites. That’s not something either WordPress or s2Member are designed to handle just yet. However, s2Member does support support for API Functions that provide a feasible work-around in some cases.

Please see this article in the s2Member Codex.
See also: http://codex.wordpress.org/Function_Reference/current_user_can_for_blog