I found some cases just kike those, without the holes, at a dollar store. Clear plastic with a pink (ouch) hinge and latch. Not the strongest things in the world, but after some very unofficial testing, they will keep things dry if they don't go toooo deep, and not tooo much weight is placed on them. They are a little larger overall than an Altiods can, and seem to hold a little more, altho I feel that they are a little harder to pack, since you are packing from one end.

I personally like just putting bandaids and such in a snack sized ziploc bag. Makes stuffing the kit a little harder, but keeps things dry.

I am going to experiment with using that black rubber tape that electricians use on outside connections (this stuff is backed with a strip of blue plastic on the roll, you peel it off as you go, the rubber tape then somehow bonds to itself) to wrap the outside edges or maybe the whole thing) of an Altoids can and see if that make it more waterproof...