So I'm setting up a small 9.5 tributary, and was looking for a cheap dry box, and found these:
Stanley Hand Tools :* 028001L *-* FatMax® 28" Structural Foam Water Resistant Toolbox
they have them for $29 bucks at Home Depot (and a 23" version at Wal Mart for $20). I have held it under water for several minutes with no water getting in, and they are super tough stuctural foam (like a pelican case) with tight closing heavy duty latches.
another great benefit, is there is a horizontal groove in the top of the case (for cutting pipes)) that happens to be the perfect height to allow the crossbar of my frame to lock the box to the boat. no straps needed.
Just thought I'd pass this find on, as I have been helped so much by ideas in this forum...