The epic gems will be made available via Alchemy transmutes, purchasable with honor or emblems of heroism, and through prospecting Titanium Ore.

Currently on the PTR it is 20 badges or 10K honor to purchase.
And yes it is a good source of gold. Also, don't forget you can buy honor from Stone Keeper's Shards (30 per 2K) and Arena Points (100 per 2K) as well.