Mouthwash was on my grocery list this week as we're down to the last bottle and even that is only about half full. Thankfully Walgreens has a great deal on them! It's a monthly megasaver deal and honestly I need to double check the end date on it. I'll try to edit later with a date if anyone else is interested in trying it.
Right now the mega saver is the 500mL bottles of the cool rinse Listerine. It's the blue bottle and it's 3 for $9. Coupons.com has coupons that are $2 off 1 bottle and are good for this particular one. You can print up to 2 per computer so use more than one computer to get multiple sets! Using 3 $2 coupons will bring the balance down to $3.
Now if you have any prior register rewards, I had $3 ones from the aquafresh deal last week, you can use those to pay. You'll just need to use a small filler like the ramen noodle for $.29, so that you have 1 coupone per item. Then you only pay for the ramen noodles. I even check out the clearance rack for cheapo items. Last time I scored a bunch of pony tail holders for Monkey for $.20 each!
Even if you don't have a prior register rewards you can still get them technically for free. With this deal it spits out a $3 register reward good on your next purchase, not including another listerine deal. Meaning you can't roll that reward into another 3/$9 and get a 2nd $3 reward. Either way it's a good deal cause you'll either just roll the $3 reward into a new one or break even.