Until Blizzard decides to let us take a character straight from level 1 to level 70, I'm pretty much stuck going through that content. I enjoy learning to play new characters, but I don't think just grinding out quests does that for you. I would really like a 70 of each class so I can learn how to play them in dungeons and eventually the lower tier raids like Karazhan. Since I can't skip all of that content I've done endlessly already, I try to make my trip to 70 as easy as possible.
It was when I started levelling my Frost Mage that I realized just how far I will go to speed up those early levels. About 5 minutes after I rolled that Mage, I equipped her with a set of pre-enchanted gear that gave her just under 100 Frost Damage, and roughly an extra 400 hit points. I was basically invincible, and I loved it. It was expensive, but so worth it to blaze through those first few levels. Taking out moonkin in two Frostbolts was strangely soothing.
That's the most money I've put into a brand new character so far, but I would probably do it again in the future just to bypass that really early stuff. My question for all of you is: What's the most you've put into a twink that fresh, just for levelling and not stomping WSG?