Unfortunately, the short answer is a headlamp like that doesn't exist to my knowledge; mainly the waterproof part; without buying an overpriced specialty headlamp. The only thing that comes to mind is a
stenlight.
The most expensive headlamp I personally own is a Black Diamond Solaris. They're on sale at sierratradingpost.com still I think. However they are definitely not worth the retail price. I was quite disappointed in mine for the cost. At the STP price I'd consider it an okay deal.
The good part is that the solaris is a rechargible light that has incan and a bank of 4 5mm leds (small ones that give off an angry blue light).
The bad news is the light isn't very rugged, and definitely not dunkable. The battery pack is also large and stuck to the back of the headstrap.
LED headlamp technology is wayyyyyyy behind. Like 3 years behind technology wise. Most headlamps are abysmal in output and runtimes. (mostly due to cheap 3AAA battery packs
)
In order to get a half way decent LED headlamp you have to mod your own at the moment.
LEDs, a quick rundown.
Lumileds is a company owned by Phillips. They make the Luxeon brand LEDs... Luxeon I, III, V, K2, and Rebel.
Cree is a company that makes the popular XRE LEDs, you'll often see Crees referred to by their bin. (P4, Q2, Q5, R2, etc.)
Seoul Semiconductor is a company that uses the Cree die and coats it with their own phosphor process. SSC P4 U-bin LEDs are commonly used in modding headlamps.
These are the current major players in power LEDs. Luxeon I, III, and V and some K2s are old technology that has been surpassed by Cree and SSC. Luxeon I's (1-watt rated) and Luxeon III's (3-watt rated) are what are found in virtually every production headlamp along with 5mm LEDs.
Watts simply refers to how much power an LED eats up. Two years ago watts meant something, but nowadays it means almost nothing. It became a marketing gimmick to those who are unenlightened. So ignore watts for the time being.
You have much to read about and learn. :welcome:
Try asking LED questions in the LED forum after you've read up a bit more.
Hope this helps.