Are my basic assumptions about the numbers correct in Columbus?

[Carlos Castillo]

A 40k 3bd 2bth house in ohio has a mortgage of roughly 300 monthly with  20% down. Rent in the zip code of 43204 for this is on the low side 700 monthly.  The fee for property management, since Im out of state, is 100 month roughly. 
So...
$700

-300

-100

= $300 monthly?
Am I missing some big number here? Because this looks like great cash coming in. TOO good. It cant be right.