Every year in the summer, on the 3rd sunday of every month, between april and October, MIT has a swapfest. I have been attending this swapfest for the last couple of years and you never know what you can find. This is a place to buy, sell, and swap amateur radio, electronic, and computer equipment. Many times I have found good deals on old games and books. Be sure to take a copy of the flyer to get a discount on your entrance fee.