Comparison Shopping Engines: Shifting E-Commerce Sales Into Overdrive

I'm no expert in the logistics behind comparison shopping engines (CSEs), but I am definitely an expert in using them. It's as simple as a Google search, and voila, you have a price comparison of the item you desire from sites all over the internet. It's just so darn convenient! Why would anyone want to take on a crowded mall when they could order all the same things, at more competitive rates, from the comfort of their home?