Most real estate agents can set a price on a home the minute they walk through the door. If they have a lot of experience in a market, they know how well a neighborhood holds its value, too.
While anyone can spend a few minutes online and pull information on sales of comparable houses, real estate agents have the experience to know whether a specific house is overpriced or underpriced. In the best-case scenario, an agent will have such a good idea of what you're looking for that she won't even waste your time touring houses that won't work.
Not only can agents provide all the data on local home sales that you want to see, but they can also bring assets to the deal that come from years of watching waves of transactions in the neighborhood.