*sigh*.
Buying gold is not needed for any game.
If you buy gold you run a risk of being banned in any game you bought gold for as that goes against their terms of play, something you agreed to without reading.
Also buying gold can come with risks, as credit cards are stolen, or gold not received.
And finally, buying gold continues to support the bots and the other issues most people have with online games, if there was no market there would be no bots or spammers.
Really, just don't buy gold or guides just work at the game and you can earn enough to support your character.