I didnt have enough money to buy a mount at 40 or an epic mount at 60. These all came about 4 levels late. I used Gold I had on mains to buy the non epic ground mount.

I think I leveled fast. 3 toons to 70 in 11 days 20 hours. Speed was most important for me, so like others suggested I skipped doing professions while leveling because I barely had enough bag space to loot corpses let alone pick up herbs, leather, and ore. Leveling the three professions while leveling will cost you anywhere from 5-60k xp/hr depending on your level (dont forget to take into account the extra AH time, Auctioneer is assumed). But you'll get your mounts 4 levels sooner.

You could make the argument that the time will be made up when you're riding around outlands 40% faster then me on my normal mount. Maybe? Four levels is a lot of traveling, but with the shaman class I minimized it as much as I could by using flight points and Recall. Less time on the slow mount then other classes.

My advice would be to do only leveling. Bag Management X3 was enough trouble for me. I had my epic mount by 64 and the income from outlands quests was great enough for me to buy a flying mount as soon as I dinged 70. I've been leveling my professions while waiting for BG and Arena Ques in Org. Seems to be working well.

Professions are a must, you are going to need the Gold for Repair Bills alone.