I have to advise someone who needs robust e-commerce and inventory tracking software that includes barcoding, sales and also rental tracking via a visual database.

They are looking at Filemaker and Lightspeed, what the Apple Store recommended to her. I was looking at this demo:

http://rentalbookingsoftware.com/?gclid=CNu9tKTE4LwCFW9p7AodK08AjA

Magento is open-source and I think that is a good idea.