If you came here looking for pvp gear to purchase, you can see my list of honor gear prices here
Apparently Blizzard has started listening to the people who were objecting to the 75k honor cap, especially since there was no way to liquidate the honor once you were already at the cap. In order to solve this, blizzard has made a change that was not mentioned anywhere, until now.
They have given the jewelcrafting vendor in the Orgrimmar (alliance will have their own equivalent) the ability to sell you blue gems for 10,000 honor points. Yep, you heard right, at the honor cap, you'll be able to buy 7.5 scarlet rubies and either sell them straight away or cut them and sell. It is a pretty good way to deflate the market however, especially since a lot of people predict that gem prices will slowly skyrocket when season 6 begins and ulduar easy mode enters farm stages and people grab tons of new gear with sockets.
For the horde, you will be able to buy them from lady palanseer
It would be best to slowly sell half your stock at the highest possible price you can fetch, and then keep a watch out for the next gearing phase of 3.1, likely within a few days to a week. So for those of you who are honor capped and have nothing else to buy, do so now! You might want to spread this knowledge out to your friends as fast as you can because when word gets out (like if it makes it to wowinsider) another horde of gems will start flooding the marketplace!
You might also wish to check out how to turn your wintergrasp tokens into gold here!