The spectral tiger mount isn't very common, but it can be purchased with real money. A friend of mine ordered several boxes of the WOW Trading Card Game in order to get this mount. The only difference is that Blizzard didn't get his money directly, but they definitely got paid.
The upcoming Starcraft II collectors edition will have a Warcraft non-combat pet included.
Pets and Mounts have been provide as part of the Blizzcon ticket price.
If anything it's more honest when blizzard provides access to these "paid" vanity items directly instead of through some sort of marketing gimmick.