Walmart (and various third-party merchants) cuts up to 60% off a selection of raised garden beds. Plus, orders of $35 or more qualify for free shipping; otherwise, it starts at $5.99. (Select items may also be available via in-store pickup.) A couple of best bets:
BCP 8x2-Foot Vegetable Raised Garden Bed for $64.95 (pictured, low by $29)
BCP 3-Tier Raised Vegetable Garden Bed for $84.95 ($115 off)
If you aren't using any of these three methods for significantly saving on laundry detergent, you are washing money down the drain.