I am curious, do you know ANY a good small shopping cart that does PHP/mySQL even it can support PayPal payments. I am hoping a free because I want to test something.

I know NOTHING is free but at least if it had one exist :D

You mean something like osCommerce (http://www.oscommerce.com/)?

There is a good CGI cart, Agora:

http://agoracgi.com/