You can check around basic sites like newegg or tigerdirect for sales and stuff on refurbs etc. Ebay is pretty decent too if he/she is more dedicated and is willing to wait around and try to snipe up a good auction.
A a lot of retailers will have good deals on new laptops at that range too. My friend purchased a pretty decent machine for 400 (100 dollars off from a sale for something), and does not have to deal with it being a refurb or discontinued product.
Also, each brand has good and bad models, but stay away from Acer and Asus.
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Chrono1219