Amazon offers the BlueMagic 900 Carpet Stain & Spot Lifter 22-oz. Can for $3.77. Add it to your cart via Subscribe & Save to drop it to $3.20 with free shipping. That's tied with last week's mention as the best price we've seen. (It's about a buck under what you'd pay in local stores.)
Be sure to cancel Subscribe & Save after your order ships to avoid being billed for subsequent shipments.