
So the solution to my problem is going to Mambo CMS for this particular site I was building, they have a component(module) called Mambo PHP-Shop that is a shopping cart that can be used as a catalog only and can track inventories. Very good integration with the CMS, the only downside is I have to learn a new CMS, but thats ok it pretty easy, lots of reading the docs and forums at first.
Other than that all my other sites are XOOPS sites. I just hope somebody can come up with a stable porting of a shopping cart for XOOPS soon.
Hope that helps