Free Shopping Cart Software for Joomla!
You can choose from many of the better store options available for Joomla below.
Joomla Extension eCommerce & Store Solutions:
VirtueMart Store (VM2):
HikaShop is an E-Commerce extension for Joomla 1.5 and 2.5. It is built for simplicity and flexibility.
HikaShop also has a wide range of marketing tools, but also powerful statistics displayable on your HikaShop dashboard to help you manage your store.
It provides advanced taxes, zones, languages and currencies management for worldwide sales as well as advanced customization capabilities of your online shop in order to meet your website ecommerce needs.
VirtueMart is an Open Source E-Commerce solution for Joomla!.
VirtueMart 2 Features: http://virtuemart.net/home/features
VirtueMart Extensions: http://extensions.virtuemart.net/
VM2 PayPal Pro plugin:
VM2 UPS plugin:
In the past VM had these as free, the new VM2 still has the core as free but allow 3rd party plugins that are free and commercial this is still an on-going process and takes a little time to evolve.
With open source there is also the option to custom develop them.
Please note that for any commercial or free extensions, the vendor will support any internal issues.
I try to provide recommendations solutions, some solutions are a combination of free and commercial, but some of those solutions are new and/or untested.