On a per unit basis, you won't maximize your return through turnkey purchases. Your mission statement might be 'maximize return on a per unit basis while investing only in turnkey'. This would possibly maximize your return for minute of time invested in procuring real estate investments. Common buy and hold strategies in order of highest return& work/involvement required:
1. BRRRR - buy distressed, full rehab, rent out, refinance, repeat.
2. MLS property - buy nearly move in ready property off MLS or other sources, hire PM services
3. Turnkey
Note - in my areas, it still doesn't take too long to find $200 cash flow properties in the $70,000 ballpark if you pursue strategy #2. Or $300 cash flow in the $95k ballpark. Now, if you are taking a turnkey providers proforma cash flow number as your $250, after looking at dozens of them I am confident you need to reduce that number substantially to reflect the true long term cash flows of the property. If you post sample numbers I will point out why that is, or eat my words.
Strategy # might seem daunting to manage from out of state, but you are already here doing research, and with the right references and help you could do it.
Good luck!
Cliff