I watched the video and read a tutorial, and after some trial and error I created a page with three products on it. It looks okay, but the minute you add anything to the cart, the top of the page displays this text:
Warning: number_format() expects parameter 1 to be double, string given in /home/ (blah blah blah) wp-content/plugins/wordpress-simple-paypal-shopping-cart/wp_shopping_cart_misc_functions.php on line 40
Also, price does not appear in the shopping cart and changing the quantity is not possible.
I'm getting punchy, so I'll look at this tomorrow. I'm not a coder, so it might be something simple that I just don't see.
This site needs to go live in a few weeks, so if I cannot figure out a solution, I'll remove the plugin. It would be great to make it work.