Cherry-picking rehab costs won’t give you the full picture since everything ties into existing systems, permits, and infrastructure.For a garage conversion, you’re adding sqft  which means extra costs for HVAC, insulation, electrical, and possibly new windows or structural changes.

Expensive and a little scary for me personally.

I have been listening to The Real Estate Rookie and other BP shows for about a year.

This is for personal clarification. 

LLC Taxation for FlippingSince you’re flipping the property in under 12 months, the IRS usually treats it as ordinary income because it’s considered a business activity, not a long-term investment.

The lease would establish income, which can be used for loan qualification purposes.

For investments, you'll likely want a conventional loan for commercial properties.

Go for projects that needs rehabs and get into flips/BRRRRs. 

Not sure what you are looking for.

For example, index funds could be a no brainer for investing in the stock market.