I am doing a project where the shopping cart has products that have like 5 sub-categories and are also linked by manufacters, catorgories, and models. Does anyone know of any cart systems that can support a complex product system like this? I am trying to avoid building a cart from scratch.

Also, I am looking to implement a very graphical interface into it so it will have to have a very custimizable face to it.

You might contact http://www.sitetutor.com - they have a hosted ASP cart that is prety customizable depending on your needs.