While I as an developer, likes the ability to get a solid base and enhance it from there, this base is in my personal view a little too rough. While the screenshots I am showing here are really looking bad since I didn't bother downloading the images I saw directly this was nothing for me to build upon. I know - this example is not meant to be more, but all I am saying is that there are more solid foundations to start from if you are about to implement a asp shopping cart.
The product catalog
The Cart
The total
The code is really simple - no database at all, instead it shows you some nice array handling techniques which it worth looking into.
ASP101 Shopping cart