DaKine Drafter Bike Backpack for $35.99 plus $7.25 shipping, making the total $43.24 shipped.  Here is a screenshot for your reference.  It is available in Black, Logger Flannel, and White Box colors.  This bike backpack features a Nalgene 100oz/3L reservoir with Aquaguard anti-microbial, breathable Dri-mesh back panel and shoulder straps.  It usually goes for over $65.