2011io000oi via eBay offers this GSH 7-Liter Men's Military Shoulder Bag in several colors (Tri-Color Desert Camo pictured) for $8.99 with free shipping. That's tied with last week's mention and the lowest price we could find today by $4. This waterproof bag features a ventilated back panel, an adjustable sling strap, and several pockets.
Note: It's available in A-TACS Arid for $7.99.
Before you spend another dollar on items and services like these, check with your public library. You will likely be surprised by what it offers for free.