Try American Apperal or Von Dutch.

Well I might be dating myself here.. but when I was in college I use to carry around an army messenger bag and I loved it.. it was resiliant. 10 years later, its still in the condition I bought it in… but don’t cringe… it wasn’t camo or anything, just a plain green. Back then though, they were “in”. Any army surplus store will carry them. If that really isn’t your style, try http://www.ebags.com. That might be a site that carries the largest selection. Also if you want right vintage (and not just the “look”), I would start hitting goodwill and Salvation Army stores. It might be ancient, but you’ll get a bargain. Excellent Luck, and Pleased Shopping.