Integrate items in Invoice with website in Site

Integrate items in Invoice with website in Site

I use Invoice which I love.   I have about 100 items that my customers group together to produce a finished product.  I have a website that allows me to group those products in categories and display them with images and descriptions.  I use Joomla and Virtuemart for that purpose.
That means I am maintain two lists of my products.

I have been looking at Site and it would be wonderful if I could somehow use the same database for both my website and my invoicing.

Is there a way Site can me made to use my Invoice data.

David Joseph