Walmart offers the Ozark Trail 40-Liter Eagle Hiking Backpack in Blue or Grey for $21.23. (Blue is a few cents more.) Opt for in-store pickup to avoid the $5.99 shipping charge. That's a $3 drop from our mention from three days ago and the lowest price we've seen. (It's the best deal now by $19.) It features air-mesh straps, an adjustable back panel, and rain cover.