Question : Subdomains and SSL for Ecommerce

I need to set up an ecommerce site that looks like this:

Home page will re-direct you to your local "store".  All stores will have the same basic products and lots of the same information.  They'll use the same web programming I write to control most of the layout and functionality.  

So I want these "sites" to really just be one site with different sub-domains for each store.  Because each "store" represents a different dealer located in a different geographic area, they all want their own domain names.  It being an ecommerce site, when they check out, I'd assume they all need an SSL cert.

I don't know much about SSL and the different types of them.  Would a wildcard work for this even though it's different domains all on the same IP address?  I'm using cPanel, if that matters.

What's the best way to get this done?  I don't really want it to be separate sites with separate IP's because of the extra cost involved, but need to know if that's necessary?

Answer : Subdomains and SSL for Ecommerce

oops, I assume you misunderstood my technical description, at least partially, and also my jokes ;-)

Anyway, I'll try again:
 You have a bunch of data, html file, scipts, images, whatever which are (should be) common to all of your clients (which each wants his own subdomain).
 Based on that, the technical solution would be to setup name-based virtual hosts, one for each subdomain, where they all use the same DocumentRoot directive (speaking in apache's httpd:conf terms).
  This should solve all you organisation problems like editing one css only which is (virtually) used on 25 doomains. Right?

The problem you have is with SSL, as name-based virtual hosts do not work with SSL out of the box 'cause the web server (apache, the httpd process in particular) has no idea which FQDN was used by the browser as this information is only available in HTTP which is a application level protocol protected by SSL.
This is a design problem in SSL. But there exists a workaround based on new RFC (see previous links) which allow the browser to use an attribute in the SSL protocol to pass the FQDN which then can be extracted on the server (apache) to identify the real host (virtual host in apache).
If that workaround -SNI - Server Name Indication- is implemented in the server, then you can have multiple unique certificates for the same IP. If the browser also suppports SNI, then this browser will be connected to the server specified by the FQDN.
Again, the workaround is SNI, which makes name-based virtual hosts possible with SSL, which otherwise would not work.