Steve,
I've got Ikelite DS-125s. These are powerful, but if you are using them on slave mode you don't get many power settings. You can get a TTL converter, but that's more expense. The 125 and more expensive DS-200 are both rated to 92m (300ft) - can't quite remember if that was quite enough for you. There are then Nikon SB-105 (quote old, but mighty fine piece of kit), Inon D-2000 and Z-240, most of the Subtronic range and Hartenburger that are 100m rated.
This will let you find out and compare specs:
Underwater Strobe Comparison Guide - Digital Diver Network.
You can pick up SB-105s and DS-125s cheap second hand,
Wetpixel.com :: Underwater Photography and Videography is a good place. The Inon's look good (plenty on here and Digigreen that have them). Subtronics are pricey - but you get what you pay for. Don't know anything about Hartenburger.
HTH,
Rob