Powerful Window AC, $250

Frigidaire FAS156NIA2, 15,100 BTU, only 2 years old, stored inside over winter, in great shape and cools giant rooms up to 880 sq feet! If you have a big apartment, a floor-through brownstone or a loft, this is the air conditioner for you. It’s one of the most powerful ACs you can buy which run on 115VAC. Installs in a regular window with a ledge. Includes remote and energy saver mode (Energy Efficiency Ratio: 10.7). Come and pick it up in Prospect Heights and say goodbye to the summer heat. $250 (paid > $450 new).

Here’s a link to a similar model:
http://www.frigidaire.com/products/roomair/window_mounted/median/prod_FAM156R1.asp