buying an epic mount is NOT high on my agenda.
900g for merely a speed increase?
at lvl 60, there honestly isnt a whole lot of rushing on ground. anybody who plays THAT much is mocking themselves if they say they are "saving time" with such an investment. in cases where it's actually important to be somewhere quick... you likely have a warlock who can summon you. let's be honest.
the best justification people can give is that it's good for pvp. 900g for a slight edge in running for your life (or chasing some dude) is absurd. there are about 30 things at the AH you can buy which can more aptly save your life or stop that runner... for a heck of a lot less...
the epic mount is more like a case where lvl 60s need to make the game meaningful, so we save up for the next cool thing. to me, until battlegrounds exist (which i think will make having epic mounts valuable), an epic mount is a waste of a ton of gold/energy when you could be investing in other stuff or just relaxing and playing the game.
my gold from my lvl 60 is mostly going to alts and gathered by casual play at this time.
when i need an epic mount (if i ever really do), i'll get one. 900g saved can go to cool trinkets in the mean time.
and having the best trinkets is WAY COOLER than having an epic mount