Buying newer builds for rental strategy. Need help.

Thinking about buying some newer build homes that are turn key for long term rentals. 
BUT if you’re not buying in all cash and going to finance it. How much do you think you need to make on top of the mortgage to make the deal worth it? If the mortgage, PMi, Insurance and taxes are for instance $1,900/mo. Would it be worth it to rent out for $2200-2400/mo? How much do people usually put away for future possible repairs etc? 
I’m having trouble figuring out what would be considered a good deal.