Going to spend Christmas at the FIL's house on Sanibel, and my son and I want to escape for a couple days to KL.  He wanted to do a night dive while we're down there, so I need to find him a dive light.

Any recommendations on a reasonably priced light for a teenager?

Have a look at DGX. Their 600 LED light is very nice.

https://www.divegearexpress.com/led-dive-lights

Princeton Tec Torrent LED uses AA batteries and is $55 on Amazon.  Perfectly adequate for occasional use.  The biggest con is the size as it is a little large for putting in a BCD pocket.  Add a wrist lanyard and clip.

I have been using a SeaLife Sea Dragon Mini 900 lately as a primary light for cavern diving.  Very bright and has a good beam pattern.  Fits in a BCD pocket and operates with a push button, so it is easy to use with one hand.  $99 on Amazon with battery and charger.  Extra rechargeable batteries are $10-15 dollars.

I have that SeaDragon Mini Light. Love it.

I have a Light and Motion GoBe for my primary (rec) and carry a Princeton 260 Lumen in my pocket for day time and backup at night.

https://smile.amazon.com/Light-Motion-White-Outdoor-Flashlight/dp/B016LCV9DM/ref=sr_1_3?ie=UTF8&;qid=1544013357&sr=8-3&keywords=gobe+dive+light

I have alot of L and M gear, and really like it.

Thanks for the recommendations, everybody.

He should be able to borrow one from the operator.

If you're just doing simple open water night dives then I would also look at the Big Blue dive lights.
They sell a combo pack with a 1200 lumens primary + 450 lumens backup that works great for basic open water dives and comes in at a reasonable price for a set of dive lights.