Got My Mind On My Money

Where's the Golden nugget companion for this?

Not even to 100k.

TL;DR = All of the raid instance bosses will drop gold based on the following formula:

total gold dropped by boss / number of players that killed boss

If you plan on farming gold by killing old raid instance bosses, you'll be unable to.

In general, enemies in raids and dungeons drop significantly more gold than outdoor foes, specifically because we are assuming that the gold is going to be split 5, 10, or 25 ways. As player power rises over time, it obviously becomes possible to complete old content with significantly fewer players, such that the gold rewards become disproportionately high.

In the past, our only solution was to drastically reduce the gold dropped by legacy content across the board (e.g., Magtheridon, much of Karazhan, etc.). In Mists, we have a new system in place that normalizes gold yield based on the number of players involved in the kill. If a Black Temple enemy drops 100 gold today on live, and you kill it with a 25-player raid group in Mists, it'll also drop 100 gold and each player will get 4 gold. If you solo Black Temple, that enemy will also give you 4 gold. If you do it with 4 friends, it'll drop 20 gold and each of you will get 4.

In other words, the gold obtained from killing raid or dungeon creatures no longer depends upon how many people you bring, or do not bring, with you. This system does not apply to anything in the outdoor world.

http://us.battle.net/wow/en/forum/topic/6147286884#9

The absolute best (or easiest) way to earn this achievement is by Pick Pocket(ing) mobs as a rogue in Pandaria, hands down. You will at most receive up to 2g per pocket picked, but it usually varies between 10s and 1g. In the best spots you will loot around 60-80 [item=88165](es) per hour and they will contain approx. 14g each. That means you will earn between 840 and 1120 gold per hour from [item=88165](es) alone, not counting the gold earned from pockets. (You will also loot a lot of greys which will sell for quite a lot, but obviously won't count towards the achievement.)