I'm not aware of any parts available to build laptops. However, the parts availability for towers is limitless. Newegg.com is the best; great prices, super fast shipping, and a large variety of parts.
I am looking online....no luck so far. The annoying things about customization like Dell offers is that rarely can you go DOWN significantly.
I really do not need the latest processor. I can get by on a 1.5. I will put the latest and greatest on my desktop anyway and leave the laptop for simple web surfing and typing, as well as some games in case I travel.
Oh well. Newegg is a great site...I have seen that one before.
I guess for notebooks, buying used is the best bet for cheaper prices.