You're probably already aware of these, but for the benefit of the community I'll share my two favorites for buying hardware in genera, not just notebook parts.
Pricewatch allows vendors to submit their prices on a wide variety of hardware, it produces a search-engine like interface based on price and model of the hardware. Of course this doesn't mean the vendor is reliable or honest..
I use
NewEgg whenever I can. I've bought digital cameras, thousands in desktop hardware, and about a thousand dollars in laptop gear from them. Their prices are almost always reasonable, great selection of OEM and retail stuff. They ship fast and while I've never needed any of their support or RMA anything, the anecdotal stuff I've pulled from forums, blogs, and reviews all say they are really professional. If it comes down to saving a few bucks from a place I've never heard of or spending a few extra dollars at New Egg, I'll usually go with NewEgg.