If anybody has a free sec could you take a look at the avett brothers shopping cart

http://theavettbrothers.kungfustore.com/

and give me your thoughts on how they might be implementing their shopping cart? I really like how they have jquery integrated into the cart and how it is HTML/CSS based. I would like to try something similar.

Or if anybody could suggest a cart that I could use to achieve something similar, that would be very much appreciated as well.

I have the template pages already mocked up with the jquery and now just need to "cart-isized"

thanks.