I use a Watershed bag. They are depth rated to 300'. I have used mine in my 10 ft fishing Kayak for a little over a year. They offer an optional bag liner which can serve as padding which I also bought but I find that it takes up too much room when inserted in the bag. I pad mine with a towel in the bottom of the bag. You can check them out here.
You may find a better deal with the link below if inerested.
I did not check Amazon but they would probably have them as well.