I've met many a pornstar/actor over the years and I've never been quoted $500 per hour ($350 has been the most, $200 the least). The most per hour I've been quoted was $400 from a non-porn actor. I did not see that guy.
A lot of people assume just because someone is a popular porn actor they'll immediately ask a lot more. Yes there are those that charge super high value (Cade Maddox comes to mind), but $500 and above has not been the norm, in my experience anyway.