REI Garage offers the Gregory Pace 3 2-Liter Hydration Pack in Moonrise Purple or Aero Turquoise for $48.73. Pad your order over $50 to bag free shipping; otherwise, opt for in-store pickup. That's $50 off and the lowest price we could find. It features a zippered main compartment, trekking pole storage pocket, stretch-mesh external pocket, accessory pockets and a gel flask holder.