If you purchase the game directly from Funcom, they do accept PayPal. You can link to the digital version purchase page directly from The Secret World website.
(Edit: Digital download is also available through Steam and the Origin store, both of which also accept PayPal.)
One caveat: I'm not sure whether their system is going to want to link your Funcom account with the download, or whether it will simply send a code to be activated by anyone. (A friend bought the game for several of us and sent us the codes, but that was at launch; it's possible things have changed. Might want to check with the company just in case.)