Eddie Bauer offers its Eddie Bauer Stowaway 10L Packable Sling Bag in several colors (Atlantic pictured) for $18. Coupon code "TRAILMIX" drops it to $16.20. With free shipping, that's $14 off list and the lowest price we could find, although we saw it for a buck less in May. It's water-repellent and has two exterior zip pockets, an interior slash pocket, and two mesh pockets.