Is it difficult for PTC sites to use paypal?

In reference to your comment about using a bot to send money, many online paying programs utilize what's known as PayPal's Mass Payment feature. You can read more about how this works on PayPal's website. Here's the overview page: www.paypal.com/us/cgi-bin/?cmd=_batch-payment-overview-outside And here's the "How it Works" page: www.paypal.com/us/cgi-bin/webscr?cmd=_batch-payment-works-outside