here is a side by side comparison that i found useful http://www.fixedgeargallery.com/reviews/messengerbags/

i have 2 from that review not the actual bags but ones that i bought that are reviewed there. they make a few mistakes and the pictures of them riding with the bags look funny but side by side is a good way to compare.

in the end you get what you pay for, so if you want a "standard" bag then a buck fifty for a chrome is pretty standard. if you want a cheaper one they have banjo brothers and timbuk2 reviewed. if you want handmade attention to detail and expect something made to your spec then you have to buy from the more expensive companys