.: Is he running a car repair business, recycling business of some sort.

In the Denver area it was almost an entirely cash market--we once received payment of nearly $50k, in one hundred dollar bills, in recycled baby wipe tubs.

For keeping things within budget, maybe look into using recycled materials or getting discounts for buying in bulk. 

You just gained $40k in equity, take the $40k and recycle it to buy another property (that's the repeat part of BRRRR method).

it is no news here that BRRRR is an awesome Real Estate strategy that build wealth and cash flow by recycling and growing capital. it is something investors have been doing for years and are still obviosly doing today.

That's how I cobbled together my initial capital.Then it was about building as quickly as possible and recycling cash via BRRRR's. 

Rents are higher, income is better, appreciation is higher, your basis is lower, and you have much more equity to recycle that cash.

An enlightening example, is the owner of a corporation diverting unreported corporate funds to a safety deposit box, mixing in his own funds, and then spending $10’s of thousands of the corporate funds for his own personal investments, and use.

They get recycled for the metal.

I'd use that cash as much as possible when you can add value to the property and can "recycle" that money again for your next property, so that you can keep expanding!