Right now they are BOGO for $4.79 each. On https://www.coupons.com there is a $2 off coupon. Print 2 of them and use them with the BOGO sale. You will pay 79 cents plus tax for 2 warming units with oil bottles included.
Also after printing 2 coupons from that site, you can go to https://www.boodle.com and print 2 more from that site. Then you can get 4 units!!!
There is also another site that has a way to print 2 more but for the life of me I can’t find it again. It was a Glade site of some sort though.