@Dustin: Testing along the way, mechanical failure interruptions, power outages, and a variety of other things make the manual bookkeeping a challenge. I know... I'm doing that now. I Am able to keep a "hash mark" count of the millions. I just don't want to do that for the 99,999s.
@Jerry: a resettable McMaster-Carr 6-digit is $106 + S&H. Better, but still more than I'd hoped.
@Kevin: I've thought about cycle computers and pedometers, but I don't think any of them are 6-digit.
Hacking a calculator is a possibility. Just need to find the right calculator, a reed switch, magnet......
A digital counter, power supply, actuator...I'll do some searching.
Thanks all for the input.