Kurt Ullman wrote, on Fri, 27 Jun 2014 18:44:25 -0400:

Which brings up another question. Using whatever method you decide on,
how long will it take to break even on just having the current well
drilled deeper.

Good question.

How much does it cost to drill a well an additional 100 feet?

I don't know. Mine are something like 400 feet deep (I think), but
what would it cost to drill that to 500 feet? I don't know.