Its actually pretty simple.
Here is the crash course.  (Well this is how I do it)
Need a gather bot. Have him drop stuff off in the guild vault.
Get a vanilla account and use him to sell stuff in AH, make the gold.
You then need another vanilla wow account. Create a random level 1 char go to ratchet (put him in the guild to take out the gold of course). Find a seller (Gold4key, MMOFly - name a few), they will tell you what to do. You will either be in Ratchet or Org to make the trade.
I take the gold out of the gbank then just leave the guild. Not really sure if this helps keep my guild out of the picture or not.
I trade the gold to the seller, they pay. Done 
I gave up with Private Buyers, sometimes difficult to find and you can easily get scammed or something. So I deal with the $2-3 per k.