I just bought an Intova ISS 4000 strobe for U/W cave photography. It might be something that dry cavers would like, too. I haven't used it yet, other than in my house. There is only one issue that I would think would be a PITA for a dry caver... There's an on/off/flash dial that sticks out to the side. You just spin it round and round. Which means, after you're done with one series of shots, and you stuff the strobe into your pack, it's liable to get turn on unintentionally. It's probably good for scuba diving when you're only going to have your strobe out as long as your air supply lasts, and you want easy switches, especially if you're wearing gloves.
I think a caver might be resourceful enough to make a cover over the dial for transport. Otherwise, it seems to be a nifty unit for ~$135. The guide number is listed as 20 m (ISO 100) in air.
http://www.intova.net/products/new-into ... -iss-4000/