URGENT, need shopping cart solution

I am creating a site for a clothing company with about 90 pieces they want to sell on their site. I have this design I am almost finished with and would like to easily add a shopping cart to the site. Client already has a gateway through authorize.net and is hosted with webhero.com. I need a very easy cart to add to the site so I will have an add to cart box for each piece of clothing. Please anyone ?

so I can add a shopping cart using paypal and it will be easy to add to my design and also easy to add new items to the pages ?