Nate Nagel wrote:

Where do you find a "cheap" one...? I'm seeing prices of $3-400 for a
simple controller with two thermocouples.

Find the
leaks.

I know where the leak *isn't* - anywhere I can fix. There's water
coming out the bottom of the tank, and it's not coming from any of the
fittings.

Just out of curiousity, did you replace the anode in the tank every several
years. As I understand it, this can significantly extend the life.