On: Minimum wage would be $26 an hour if it had grown ...

[oh_sigh]

Do any of the results change if instead of picking a quite high margin in postholes, you pick something more reasonable? What if it takes 15 years to pay off the hole digging machine, not 6 months?

[ihumanable → oh_sigh]

15 years worth of postholes is 200 * 365 * 20 = 1,460,000 postholes, that would mean a profit of $0.0136 per posthole.

6 months worth of postholes is 200 * 30 * 6 = 36,000 postholes and a profit of $0.55 per posthole to pay down the capital investment.

In my original post I claim $5 per posthole profit can pay this off in 11 days.