If you are quick- you should be able to get a 9 Speed group set being sold off "Cheap". Shimano are going 10 speed on all except Sora for 2008- but A 9 speed 105 or Ultegra would have better components than Sora. But what is a Group set? Expensive as a one time purchase.

10 speed will give you better availability for spares in years to come- but I think 9 will be available for some a long time. I have 8 speed Sora and 10 speed ultegra and the only difference I note is in the Closer ratios of the 10 speed. Far nicer to ride in my opinion.

Crankset is where you can save a lot- or spend a fortune. Plenty of other manufacturers about that may be better or cheaper. Quality is another matter and cheap normally means heavy.

For wheels- Look at the cheaper handbuilt wheels. They are quality- even at the cheap end of the range of 105 hubs-36 spokes and Mavic rims. They will be better than a lot of off the shelf "Branded" wheels at a far more expensive price.

Then you start the real problem. All the anciliaries- Seat stem- bars- saddle- Bar stem etc.

Building up from a bare frame is going to be expensive. Far better and cheaper to get a Last years model bike at a Discounted price and will give you a better ride overall. But If I were going to get another bike- I would go this route. Remember that the frame is the heart of the bike and the better it is- The better the bike will be.

Good luck.