A few years ago I created a system using a underwater bullet cam I purchased on eBay. I mounted the bullet cam on an extend-able pole and feed the video signal into a camcorder that uses MiniDV tapes. I use AA batteries to power the bullet cam. Rather than use a system like this I would recommend something that records digitally. If you are interested I can email you photos of the system I use.
The three systems you posted links to all look like they would work fine. I was trying to save money and my system was probably less than $300 total.
