[Mimiron's Head] came up on the Black Market Auction House yesterday on my server. I had several whispers from friends as soon as it was up, and I was on the case.
Until a couple of hours to go it was only up over the 400k mark, and I put an early bid in for 500k. Then I realised that the auction would end during an alts run of Mogu'shan Vaults, and gladly got outbid. If you stalk the AH diligently enough, you can get a pretty good idea of when an auction will end. I usually try and catch the moment (or near enough) when the auction goes from long (>2hrs, <12hrs) to medium (>30m, <2hrs). Then conservatively, the auction can't end earlier than 2 hours after you saw it at long, and no later than 2 hours after you saw it at medium. I use this to help pinpoint when the auction will change from medium to short, giving me a solid indication of when the auction will end (within minutes).
For auctions that go above 500k, you can't raise the bid yourself once you have made a bid. The gold cap for a single character is 1 million gold, so you are committing half the available gold on that character each time you bid. You must wait to be outbid, collect your bid from the mail and head back into the BMAH to bid again. Engineers and Argent Squires rejoice. The timing of your bids is crucial.
Since I wanted to get to the raid, I bid 750k with less than 30 minutes remaining. Jondy checked on the auction a couple of times while I was melting the faces off the Stone Guard and Feng, and as Feng was crumbling beneath our attacks she confirmed that the auction had finished with a final price of 750k gold. I left my fellow raiders to have at it with the trash before Gara'jal and checked my mail!
Above is a shot of my winning bid. I'm not sure how long that notification stays up, so if you know - please shout it out in the comments. Almost immediately after my win, [Invincible's Reins] came up on the BMAH... not only did I get another series of whispers, but some chatter over mumble. I was pleased to learn that the new mount went for
625k 610k*, but I just couldn't justify another huge spend.
I'm very excited to have the mount, and have been riding around in it with all my characters. The purchase took me just under 1 million gold, so I'm keen to save up for some of the other mounts Mists of Pandaria has to offer.
* Edit: Jondy managed to spot someone flying on Invincible's Reins, so I jumped onto my horde Warlock to have a chat.