The Wallyies in these parts carry a pretty good generic copy of a high quality roll-top dry-bag sold under the Coghlan's name. These are a fairly heavy yellow PVC reinforced with a polyester or nylon scrim. They are asking about $17. I have two. I bought three and had to return one before I used it because a seam wasn't welded correctly. Their quality control is minimal so it pays to check closely before you buy. The first two and the replacement third were all good and , with the exception of where a knife was carelessly packed and sliced a hole they have worn well.

These are not expedition weight. But for moderate camping in friendly surroundings and single use in a disaster they are perfectly adequate. I converted one to a day pack by gluing on patches I got from Defender, intended for adding mounting points to an inflatable dinghy, and stringing 1" webbing and nylon buckles from the local trail shop as shoulder straps and a belt.

All told I guess this pack cost me about $40. It isn't good enough for a major expedition through the Amazon but for a long weekend hiking through the local swamps it serves.

Target also sells a workable version of a roll-top dry-bag under the Coleman brand. It is a bit thinner clear PVC with a polyester or nylon scrim for reinforcement. I have one but haven't used it much but it is watertight, I tested it out of curiosity, and the seams feel well put together. This isn't up to the same standard as the name brand dry-bags but for lighter duty or shorter duration it sure beats a thin coated nylon stuff sack or a garbage bag for being watertight and durable.