I have been riding the same department store bike for several years. Long story short, it needed some repairs and the repair guy said that it wasn't worth putting money into it. So I need a new bike. I don't ride very long distances, only about 4-5 miles per ride, but I ride at least 3 times per week during the summer. I live in a very hilly area and the first 1.5 miles averages about 12-15% grade. I'd like a lighter bike and understand that cost varies inversely with weight. I like the stability of a mountain bike and I feel safer on wider tires when biking down steep wet streets. However, I only plan on biking on roads. I'm thinking of building my own bike using a very light-weight full-carbon frame and then basic components for everything else to save cost, then upgrade later as needed. I'm willing to spend extra money on a nice bike, but at the same time not so expensive that I worry about leaving it locked up outside a store for an hour. Question I have is, what should I consider when selecting a frame? I am 5'7" and weight around 130 pounds (hopefully 140 by end of summer). I see that carbon fiber frames can vary by thousands of dollars. I am thinking about getting something like this:

http://cgi.ebay.com/2010-Full-Carbon...item5199087469

It looks like weight for a good frame is around 1 kilogram. Thoughts on this approach?