Image warning! 
So, some of you might recall me attempting with what seemed like increasing futility to buy a 'stupid deathpony.' The sorts of replies & comments I got on my (non-Petopia!!) posts & advertisements ranged from unhelpful to asinine, and I had a seller back out on me at the last moment. Finally, after another player from my realm (opposite faction, though) completed his Shadowmourne quest line, I have my deathpony!
Some fun facts... interspersed with unrelated images!
I paid 118k gold for this mount, and waited several months to get it. I was offering 100k, but Alliance is more active on my realm, and cutting the neutral AH cost from 118k leaves a player with about 100,300 in their pocket.
What it looks like as the player:
To get the gold, I grinded mining, herbalism, and prospected tons of ore for gems. I vendored a great many green cut gems (they sold for 9g apiece pre-nerf), and sold many more on AH. I used my Blacksmithing to create weapon chains & belt buckles to sell--the prices fluctuate but they're solid sellers as they're something people will always need. I ran dailies every day. I grinded Valor points and sold those BoE epics. I even, as a pet collector, sold a Hyacinth Macaw rather than learn it.
The mount's run animation is currently broken; the player rocks back and forth on it. The other horse mounts were fixed, but this one's still a bit goofy. I don't mind, though
It has a lot of purple on it in addition to the red, and depending on the lighting, can look purple, blue, black or properly blood-red crimson.
I suggest to anyone who wants this mount in the future, and reads this thread: research your realm's activity before saving up gold. It's probably far easier in most cases to simply do the quest chain on an alt if possible; I myself had a seller lined up who backed out at the last moment, and so I had to sit on 100k+ gold for several months while dealing with jerks trying to scam me (claiming they had a horse etc).
Last tidbit: This mount's *real* name is either Fury or Iydallus. Fury is Salanar the Horseman's red Deathcharger, seen in Acherus. She is also standing alongside Darion Mograine in ICC. When Mograine's disguised as the Ebon Watcher, his mount is called Iydallus. It's unknown (and GMs couldn't tell me when I asked during another ticket's service) whether this is a Blizz screwup, or whether Darion disguised his horse as well as himself when masquerading. When Mograine awards you with the mount, though, he says he's giving you the reins to his own faithful steed! Lorepony!
That's all! I'm quite happy with my Deathpony, and excited that I finally got it. Yey for less than 1k gold in my pocket now--that's a lot of digits missing!
Thanks again to everyone on Petopia who offered advice & recommendations when I was struggling to get this bad boy in my hands!
/end Deathpony novel
Congrats! 
Where there's a will, there's a way. 
