There is a waterproof digital probe thermometer at Davidson Food Equipment, but without knowing, I'm guessing it would be rather pricey.
Another option is to waterproof your next one. I lost the link where I had found the idea (I had the same mishap).
- Get silicone aquarium air tubing (by the foot) at one of the local pet stores
- Run the probe through, stopping just before the wiring
- Seal with 1-2 rubber o-rings (Hardware store, don't know the size off the top of my head)
If I remember I'll take a picture of mine and post it... it seems to work great.
Also, after ruining my first one, I experimented with a couple thermometer iterations. So now I have 2-3 in my mash and strike water. Between them all, I'm covered if one is mis-calibrated or fails.