Amazon has the Rubbermaid Commercial Products 1793546 TCell Automated Odor-Controlling Aerosol Fanless Air Care System (Black) for $1.75 with free shipping on $25 or with Prime (Extra 5% off for 5+ S&S orders). 

Aerosol refill NOT included; sold separately. Fuel cell technology delivers a precise dose of fragrance for 60 to 90 days without batteries.