Yes, this is my previous business :-).  I personally designed it and set up all the extensions (add-ons).

It is built on the extremely powerful Magento platform.  Magento allows for multiple sites from one set of products.  This allowed me to have a site just for my wholesale customers; these customers were vetted and had specific requirements.  However, it used the same inventory as the main site and it was integrated into my Quickbooks program.