Here's a quick update. I decided to ignore my own advice and bought the light from eBay. I also bought some King Kong 26650s and the Enova charger. The first problem I encountered when I got everything was that the light would not turn on. I had fully charged the batteries (the Enova charger is pretty good, although slow) but got nothing. Each battery was measuring over 4 volts, but my meter read zero when testing the 3 of them in series. It turns out the wrapping of each battery overlaps the top by a hair, and that is enough to keep the low profile positive terminals from making contact. I trimmed the wrapping a little with a utility knife, got a full 13.2 volts measurement in series, loaded the batts into the light and presto, it worked. Looked very bright.
Step 2 was to try it under water. One of the tragedies of this light is that the switch is not on the lighthead. That means mounting the awkward extra long canister in a place where you can reach the switch, such as on your waist. Not the most comfortable, but I might live with it unless I could find another way. The light turned on fine on the surface. I entered the water and went down the line to the wreck. I was trying to turn it on along the way, but thought I just wasn't doing something right. So I concentrated completely on it at the bottom. Nothing. Zip. Zilch. Nada. It was a bright enough day, so I just went with a backup light and was fine. But I guess this is why we are supposed to do S-drills.
Back at home after rinsing everything, I tried the light again. Still nothing. I opened the canister. It was bone dry and the batteries tested fine. I would have to guess that either the switch or the light head flooded instantly on its first dive. I have read about both happening on another forum.
I have written to the seller and now it is time to see what kind of customer service there is. I am going back to my original advice. It is worth paying more for the same item if you can get it domestically and not have to deal with overseas returns. Also, the switch being on the canister is a very, very big drawback. I might have to try one of the Archon lights. Still the same awkwardly shaped canister taking 3-26650 cells, but at least the switch is on the lighthead so you can backmount or sidemount the canister.
I'll keep you posted.