As one of its daily deals, 13 Deals offers this
0.5-oz. "Poo" Toilet Spray in five scents for
$3.99 with
free shipping. (The scent is chosen at random.) That's $5 off list and the lowest total price we could find. This spray purportedly stops bathroom odors before they begin by creating a film over toilet water that will trap odors.
Note that if you buy
two or more, the price will drop to
$2.99 per spay.