I just finish installing zen-cart on my site and I am not happy with them at all due to lack of poor customer. They got mad at me for tearing down their 1992 template skin and using my own template, the reason I did that, their theme doesnt match my product characteristic at all. So now as I am finish up zen cart, I wanted to take down the login and pass field, and disable everything that has to do with account creation as well. So i go on there and one of the tech support tells me "so i see that you are trying to make it a paypal store"... basically telling me to go to hell, since i will not being using zen-cart as a processor and only paypal. Yea thats what i want paypal, and when the customer is done adding to the cart and checkout it takes them directly to the paypal website to finish up the rest of work. What free shopping cart software offers this?
You can try using Virtuemart, they work with many different payment processors though, not just paypal exclusively.
U can try out Prestashop and using admin panel just enable Paypal and disable the rest ... Some Other Free Shoping carts : Opencart Tomatocart
Are you looking this shop to sell digital item? we have got some very basic digital stores in which the customers just have to select what they want and then insert there name and emails and they get to checkout via paypal http://www.scriptbazaar.com/software-stores/cat_54.html