Them being the 3 mechanicals (HVAC, ELECTRICAL, PLUMBING) and ROOF.

I'm aiming for a solid return on cash, and I agree with your emphasis on positive cash flow.

Just bought a long term rental in Florence, SC with a non-working pool (ripped liner & old mechanics).

With a savvy realtor and attorney, you can put forth a competitive offer that still protects you by waving the contingency with limited exceptions to mechanical, structural, environmental, and health and safety issues.

Bolded for extra emphasis.

@Tim Bishop  also I assume that is mechanical harvest  feller bunchers ?

However, it's important to note that these mechanisms may not cover all regions.As developers, we collaborate closely with leading real estate consultancy, valuation experts, and research companies.

You aren't doing much mechanical work on a house in Chicago in that price point with permits, etc. 

There's been a couple that I've been tempted to try but I just don't know enough about the mechanics of them that I've been willing to jump in both feet, and dabbling to me seems a good way to lose your money.

I agree with @Mario Dattilo and Roger D Jones.I think the only thing that I would draw emphasis on is what Mario said because unless it has a separate tax ID number it is not an apples-to-apples comparable.