There's a $4 coupon on Coupons.com for Glade Automatic Spray Starter Kits. Click on "household" category to the left to find it easier. Here's the deal you can get at Walgreens:
Buy 1 Glade Automatic Spray kit $8.99, get back $3 RR
Use $4 printable coupon
Pay $4.99, get back $3
=$1.99 after coupon and RR!!
*** you can use Air Wick Freshmatic refills on this, too!