Unfortunately you will probably find it very hard if not impossible to get just the power supply for those lights. In my experience with them it is almost never the power supply that goes out. It is usually one of the LED's that goes out and because they are in a series circuit (like Christmas lights) when one goes out they all go off. I've fixed quite a few of these for other members if you'd like me to take a look. Curious as to how you have salt creep inside the fixture and on the power supply for the lights as well.
I'm in Syracuse if that works for you send me a PM. Krazie