New panther mounts can be crafted by Jewelcrafters. The patterns require reputation mostly with Order of the Cloud Serpent (from Honored up to Exalted) and 600 Jewelcrafting skill. Patterns itself can be purchased in Valley of Eternal Blossoms.
A Jewelcrafter will be able to craft four different varieties of panther mounts, which can be then combined into a single Jeweled Onyx Panther, that will cost approximately 500,000 gold.
Note that either of these can be sold in the Auction House separately.
Here are the mounts with pictures, one by one:
Dawnstone Onyx Panther is crafted by combining all of the four mounts above, so the price for this one will be cataclysmic. I do not like the model personally, because it's almost the same as the new Recruit-a-Friend mount that replaced the good old rocket.
If this panther is going to become the new Vial of Sands mount is so far unkown, but it sure will be expensive as hell.