There's a blurb on the Games Workshop website that tells you how to quickly build a 1000, 2000 and 3000 pts army.
If you buy a battalion, you need to add some sort of general and maybe a wizmobile. The wizard kit is cool because you can use the wizard in combination with the wizmobile or not already. It makes 2 wizards I think and there's likely bitz leftover, so not a bad deal in itself.
Before you start though, think about what you want to do. Do you want to play competitive? Do you want to play relaxed games with your buds, do you want to collect or do you want to go all fluff? That's really the most important question you have to ask yourself.
If you want to go competitive, then read the posts on this forum and average it out. You'll need at least two battalions, plus demigryffs, a few war priests, maybe the war altar and one or the two wizmobiles, a BSB, a general of some sort (maybe a wizard lord since you'll definitely need wizards), perhaps eventually a great griffin (the kit is a good deal if you magnetized some of the options), the hellblaster kit, etc. Anyways, you'll need lots.
If you play relaxed games, then start with a few things like a battalion and use proxy to test stuff out before buying the rest.
My favorite is fluff building. You find/create interesting background and you build from there, even if the list ends up unbalanced, then you pick something from here, some from there and you convert stuff or use other ranges, etc. This is best, if you play on a smaller scale like with the "Warbands" rules, and it adds a lot of role play to the game...
Don't forget to check on Ebay or with regular games stores to find the old Empire Army box. I'm sure there are still some of those around and that's where you really get your money's worth!
