I was impressed. We use window air conditioners..a large one for the entire downstairs and individual ones for the bedrooms. Normally we'd be at $125-$150. What I did different this year was to drag out this old huge window fan and place it in our hallway window at the top of the stairs. We mostly use the lowest setting, it has 3 and med & high are sometimes too much. Luckily, even with our above average hot temps, we had cooler nights and I'd draw the air into or out of the house depending. In turn, we didn't have to turn on the ac's until much later in the day.
Here's a link to a newer version of the fan..much lighter weight and smaller than the one we have.
http://www.amazon.com/Lakewood-WCW1616-Electrically-Reversible-Thermostat/dp/B000CFCS6WThis one is similar in size and probably power..although it's a different brand.
http://www.amazon.com/9166-inch-Air-King-Exchaust/dp/B0001WYIQ4/ref=pd_sim_dbs_k_1/102-1370204-4647365