The link in the original thread died almost sixteen years ago. I wouldn't expect any to be available there.
They're trivial to source. I got mine from a guy out of the UK on eBay.
Glow Rhino looks to be a domestic source for tritium doodads. As I said, it's easy to get trit these days.
They're surprisingly bright. I have tritium markers on keychains, flashlights, knives, etc.
Highly recommended bling.