With orders of $25 or more, Amazon offers Prime members the Syba Connectland USB Oscillating Desktop Fan in Black, model no. CL-ACC65015, for $7.50 with free shipping. (Non-members can spend $35 to qualify for free shipping.) That's the lowest total price we could find by $10. It's powered via USB or four AA batteries and features two speeds and 180° oscillation.
Note that this item is offered as part of Amazon's "add-on program" and can only be purchased with orders of $25 or more.