Though related, this is no longer true. You can now purchase a lvl 90 character boost. Some power levelers have hoped for a day when you could use real money to buy individual items in-game, some times called "micro-transactions." At a Game Developers Conference 2008, Rob Pardo gave a strong indication, Blizzard would not ever go this route with World of Warcraft.
A new expansion unlocks exponentially more powerful gear, letting you easily breeze through Warlords of Draenor dungeons and raids. A great gold making strategy is to solo these challenges and amass a large amount of gold that you get to keep instead of splitting with your group. Start with soloing easy dungeons and work your way towards harder dungeons until you are comfortable enough to take on soloing raids. Speed and clearing ability is key – stick to those you can run through without skipping a beat and you will see your gold making per hour go through the roof.
Edit 20 It’s been a week since this post and a lot of people are still reaching out to me with questions which is fine. I have had a few different people reach out to me to help make YouTube videos based off this guide and more info in BFA which I’m more than willing to do. Whoever gets the videos up first I will link them here for you guys to enjoy.