As a young Alliance Mage of Stormwind, I often struggled to make gold in my early levels. It wasn't until much later, when I had uncovered the mysteries of the wow gold economy, that I realised that it doesn't have to be that way.
Now, as a level 80 Alliance Mage and servant to the Kirin Tor, I'm more likely to be found sipping Kungaloosh with mates outside of the Violet Hold of Dalaran than hanging out in Stormwind. But when I'm there on a short visit, I'm often asked by many a player, new to the World of Warcraft, at what level in the game do they really start to make serious gold?
The answer may surprise you. You can start to make gold at any level in the game, providing you understand how the wow gold economy works and have a good understanding of the ways of the Auction House. This is one of the first principles I teach in my wow gold guide.
Now what you consider to be a serious amount of gold at level 10, probably won't pay the bar bill of a level 80 player in the Heroes Welcome, Dalaran. Those players in WOTLK are burning through huge amounts of gold and wondering how they will ever pay for their new Mekgineer's Chopper or Woolly Mammoth.
The answer to the question on power leveling and gold is that your gold making needs to keep pace with the speed at which you level. So in the lower levels, you need to make enough gold to support your crafting and raiding and still have enough gold left over for your first mount, come level 30.
It's also true that the faster you level, the greater will be your ability to make gold. It stands to reason. At the higher levels, you'll have access to higher level mats and cover a zone quicker on a mount or epic mount.