With orders of $25 or more, Amazon offers Prime members the Gain 50-oz. Liquid Detergent with Original Scent for $5.97. Clip the $2 off coupon on the product page to cut that to $3.97. Plus Prime members qualify for free shipping. (Non-members can spend over $35 for shipping.) That's about $2 less than you'd expect to pay in your local store. It features scents of orange, lemon, white floral jasmine, and woody amber.
Note that this item is part of Amazon's "Add-on program" and can only be purchased with an order of $25 or more.