So the logical thing to do would be to get a Supernova kit and call it a day:
http://kayakfishinggear.com/Supernova-BasicKayakLightingKit.aspx$100 (as I am finding out the hard way) is actually a fair price for underwater/waterproof lights.
If anyone wants to piece together a kit, you can get inexpensive individual components on Amazon or West Marine, but they add up quickly.
Here are a few things I found out:
1. Make sure to buy IP68 rated lights (fully submersible) and not IP67 (submersible for short period of time). You know how rough your kayaking environment is, get something that is properly sealed against saltwater!
2. The marine grade switches can be expensive, remember you are not just wiring it up to the battery for full time operation.
3. Make your electrical connections water tight! electrical tape alone will
not suffice.