Rent-a-cop what?
I am actually really against the idea of bipeds flying and for that matter having where you could 'rent' a dragon as a mount. For one thing as character personalities go, I am sure a Lunus Dragon rather eat someone for even trying to fly on them and a Helian /may/ allow the concept, but I highly doubt it as it would be seen as very degrading.
Cause then the Dragon could ask you, "So-- if you could ride on my back, couldn't I ride on yours? How would you like that?"
Besides, as the engine goes, I highly doubt Istaria can handle the idea of mounts, as the idea of mounts/riding on fellow players has been talked about over and over again.
It really can't be done and I as a player, don't see the point of it.
Because honestly, there is no reason for mounts when you have so many portals that go about everywhere!
Also, if you want to fly, Play a dragon. Not that hard, if anything I find Dragons a bit easier to play then a bipedal, and yes-- I play both.