Sun World via Amazon offers Prime members the Toysmith Magnetic Levitator Classic Toy for $8.14 $8.06 with free shipping. (Non-members can spend $25 or more; otherwise shipping adds $4.12.) That's the lowest total price we could find by a buck. Sales tax is added where applicable. This anti-gravity magnet spins in mid-air and does not require a battery.

Of note: Several other 3rd-party merchants via Amazon charge the same price or are within a few cents for Prime members.