If you want to buy a decent amount of track, check the auction sites. You can usually get Fastrack in big bundles for a pretty good price. I've ordered around 100 pieces this way and have only received one bad piece of track. If you want new track, check the forum sponsors (links are above) as they usually have really good prices.
As a fellow new guy here, I would recommend not doing what I did: buying a little bit of each type of track to figure out which one you like/need. Figure out first what you want to do, and then buy all you need. You'll save yourself some money and a lot of heartache.
