I have one of the lightweight packable ones from Cabelas. I got it for 60 bucks a year or two ago. I love it.
The lower back pockets are pretty big, but be careful filling them with water bottles and stuff like that. Mine tore, but the inside of the pocket is also waterproof, so I stay dry.
When I was a kid, I used to take trash bags from under the trash can at the Exxon in Birdsboro before fishing Hay creek. Tear a head hole in the bottom and get fishin. It worked fine as well.