So I ordered a couple pair of the sprintaquatics mesh shoes, and already recieved them. 2 oz for the pair (their size 11-12 is what I ordered, but the little sticker on the shoes says 13 - they fit my size 12 feet okay), and they look like they would work out pretty well. here's another idea I found while this discussion has been going on;

http://translate.google.se/translate?u=http%3A%2F%2Fwww.andersj.se&sl=sv&tl=en&hl=sv&ie=UTF-8

These or something similar would be easy to make and might be nice for colder weather.