I've hit 70. I bought my flying mount (and spend way too much time exploring the air around Outland). I'm even attuned for Karazhan, and my guild is working through it. And yet I feel no pressure at all to raise that 5000g for an epic mount.
Like Moonfalin, I'm pretty "meh" about the whole thing. Yes, flying around at high speed would be cool, but is it really necessary? I'm the highest level, and I'm keyed-- where do I need to go so fast? I know that some of my guildies farmed for cash and have already picked theirs up, but I'm not bothering with it-- I've already earned about 1000g just from my normal questing and instance running, so I assume I'll hit 5000g at some point, and I'll just get there when I get there.
The exception to this, of course, is the nether drake mounts that are coming. Those I really want, either from PvP (although the PvP one is hard-- as a resto shaman, I'm really terrible in the arenas) or PvE, and I'll be willing to farm whatever I need to to get one of those. So what about you-- did you farm your way up to 5000g quick (it wasn't that hard when BC first came out), or are you taking your time for a reward that just doesn't seem that great?