I bought one from CheaperThanDirt.com. It doesn’t have a brand name on it. It’s 2 1/2” long, so it protrudes 1/2” past the front of the slide. I bought it 4 years ago so there might be a smaller one now.
Possibly good companies like Streamlight or Olight may have something is one suggestion?
And, possibly something else in search here? Looks to be EBay directed. Is mixed results, but looks like there's a few options here in lights and lasers to at least give you ideas: