Mambo-phpShop was the leading Online-Shop solution for Mambo CMS.
mambo-phpShop is free! You can download, use and modify it without any restrictions (License: GNU/GPL).
mambo-phpShop is no stand-alone script, but a Plug-in and requires the PHP Content Management System Mambo. So you must install Mambo first, then mambo-phpShop.
A bit of history:
VirtueMart began as offshoot of the stand-alone phpShop e-commerce web application. Originally dubbed mambo-phpShop it became the first substantial native e-commerce component for the Mambo CMS system. After the community forked Mambo into Joomla, the developer re-branded mambo-phpShop as VirtueMart, officially supporting the newer Joomla CMS. While current implementations may still function with Mambo CMS, and older editions of mambo-phpShop are still available to download, they are no longer actively supported.