Amazon: Tide Free & Gentle $4.18
Amazon has a good deal on Tide Free and Gentle High Efficiency Unscented Detergent, 50 Ounce (Pack of 2). The Tide Free & Gentle is on sale for $11.97. You can clip a coupon for $3.00/1 as well. With subscribe and save, you can also get 5% off, making your price $8.37 for two or $4.18 each.
Note: Prices can change at any time on Amazon. Please double check the prices before you checkout.