"This isn't so much a gold making tip as an ability to earn gold tip. If the data on the PTR is accurate and the conversion of currency doesn't change, existing heirlooms will cost 4x as much as soon as 4.0.1 goes live.
The conversion on Emblems of Triumph into Justice Points is 1:2.74. So, 40 Emblems of Triumph = 110 Justice Points. Basic chest and shoulders however are 435 Justice Points, meaning you need to convert over 120 Emblems of Triumph PER PEICE of heirloom gear. As a side note, the other popular source for heirlooms (pvp ones) is Stone Keeper Shards. These now convert 1:1.6 into honor so, while I haven't been able to visit the WG vendor to confirm, chances are this is going to be getting a lot more expensive as well.
So, buy any of the old heirlooms you're going to now, before 4.0.1. Also, don't confuse 4.0.1 with Cataclysm and think you have a lot of time, the new patch is on the PTR and will likely be released in a matter of weeks.
Another conversion of interest:
-- SidVicious of Stormreaver-Alliance"