A recent Reddit story serves as a reminder to ALWAYS keep an eye on the Black Market Auction House. Reddit user Cole_Country, playing a character named Nobody, got the 
Swift Zulian Tiger mount for just 70,000 gold on the Turalyon realm.
A Rare Find at an Unbelievable Price!
Swift Zulian Tiger used to drop from High Priest Thekal in Zul’Gurub. When Blizzard removed Zul’Gurub in Patch 4.0, they also removed the mount. The only way to get it now is through the Black Market Auction House, and the mount usually gets bid up to the gold cap. However, it didn’t come from a direct listing, instead dropping from an 
Unclaimed Black Market Container! These also usually go for a lot more, so Cole_Country was still pretty lucky to get it that cheap. Not to mention the luck of actually getting the mount from the chest!
Key Takeaway? Check the BMAH Often!
This story is the perfect example of why you should REGULARLY check the Black Market Auction House. Rare mounts, pets, and gear show up at low prices, and when you are on a low-populated realm, chances are you can land something priceless without spending millions of gold.