Yes, you can.
Please go to The Agile PrepCast Order Page and scroll down. You will see a very small link below the orange button that reads: "Order with PayPal."
Use that link to complete your purchase.
Read this article on how to pay via PayPal for more information. It is written from the perspective of purchasing The PM PrepCast™, but the instructions are also valid for purchasing The Agile PrepCast™.