OXA Fashion via Amazon offers its OXA 40-Liter Hiking Hydration Backpack in several colors (Orange pictured) for $38.99. Coupon code "OBOAGZL2" drops it to $31.19. With free shipping, that's $48 off list and the lowest price we could find. It features adjustable shoulder straps, 2-liter water bladder, and rain cover.