13 Deals offers the Energizer Automatic Slim LED Nightlights 2-Pack for $6.46. Coupon code "ENERGIZER1218" cuts the price to $3.49. With free shipping, that's tied with our mention from a week ago and the lowest price we could find by $10. They are sensor activated and measure 4.5" x 2" x 1.5".
If you aren't using any of these three methods for significantly saving on laundry detergent, you are washing money down the drain.