Woot offers HOLMES Dual Blade Digital Window Fan with Programmable Thermostat Control, Dual 3 Blade Fans, 2 Speeds, Expandable Side Panel with Additional Extender Panels, White for $24.99 (orig. $49.99) + free shipping with Prime.

Product Description:
COOL YOUR HOME WITH FRESH AIR. The Holmes Digital Window Fan has dual blade operation with two speed settings and a programmable thermostat that let you maintain a set temperature and keep air flow at a comfortable level in medium-sized rooms. The dual blade fan is designed to fit most double-hung and slider windows and includes an expandable side panel with extender screen for a customized and secure fit. Designed to keep a cool breeze in your office, bedroom or any room you wish.
 

• MULTI-SPEED - Simply plug into a standard outlet and set a temperature the two speed settings and dual blade operation keep air flow at the perfect rate
• OPTIMAL AIRFLOW - Programmable thermostat lets you maintain the set temperature and keeps air flow at a comfortable level
• DESIGNED TO FIT - Fits into most double-hung and slider type windows. Expandable side panels and adjustable extender help secure fan into larger windows
• BUILT TO LAST - Water-resistant motors allow use of the fan in rainy conditions. The white finish offers a clean timeless look
• WARRANTY - 3-year limited warranty