Well, you seem to be eyeing up road bikes... I'm a mountain biker, but I'll tell you what I did...

I got a Diamondback Response Sport at the turn of 2009. It was marked @ 100 off (350 total) since it was an 08 model. It's noted in the mountain bike forums as having a solid frame and construction, however, very mediocre parts. I've upgraded almost everything on it except the crank, which IMO is fine. I spent a few bucks and converted it. My gosh I love that thing a whole lot more now. It's solid, smooth, seems to glide real fast, everything about it I just love, and converting it helped quite a bit too.

I know by nature road bikes are typically more expensive than mountain bikes, but my story concludes I spent 350 on a mountain bike hardtail (on sale), which IMO is a great hardtail bike to buy since it actually is a very nice bike and it will get you riding that day, and over time hopefully swap some things out for better parts. Solid frame, decent cranks, mediocre components, but nonetheless it's an all in one ready-to-ride package that can handle quite a bit of abuse.

Couple that with an SS chain, 32T chainring, and a rear cog + spacer kit and I've probably spent in the area of 55-60 to convert, 350 for the bike.

Again, this is for a mountain bike hardtail. I can only assume road biking will be a bit different, and if anything, a bit more expensive. But, alas, that's my story.