As one of its daily deals, Home Depot takes up to 40% off a selection of vacuums and floorcare tools, with prices from $6.98. Shipping starts at $5.99, or get free shipping on most orders of $45 or more. (In-store pickup is also available.) Some best bets, both with free shipping:
Home Depot offers the Lasko 8" Electrically-Reversible Twin Window Fan, model no. 2138, for $49.99 with free shipping. (Amazon charges the same.) That's the lowest total price we could find by $2, although most retailers charge at least $55. It features an adjustable thermostat, automatic control, fused safety plug, and independent motor control. It fits windows from 25" to 35" wide.