Pre-written E-commerce App

First of all, I'm not a programmer. I'm trying to locate a pre-written application (otherwise I already have a programmer lined up.)
I have a business that builds customized computers. I need an interface where the customer chooses the different hardware configurations and then the page displays the updated price. If you don't understand what I'm talking about Dell and just about every other pc manufacturer have an interface like this on their websites. I've looked at a lot of sites, nearly every one of them uses asp.
I need to know is if some sort of pre-programmed asp script exists to make my programmer's job quicker and easier.