. $350/month if the area is B+ or higher. 

His salary is much higher than my other tenants living in the same quadplex, whom have no issue paying.  

There may be some different sectors out there where you could take the peak sale of that duplex and put it into some higher production. 

Doing this will result in higher fixed expenses on the borrowed money until you find a deal to invest in though.

You have many ways to get a loan but the most common ways are the following:FHA:This allows you to put the least amount of money down - 3.5%, however, you have to pay Mortgage Insurance, which can be a little pricey, that combined with the higher loan amount because you are only putting 3.5% will increase your monthly mortgage payment. 

In bigger cities even though the prices are higher you also have a higher chance of finding tenants to alleviate the higher mortgage payments.

We have insurance on it now, but it's much higher than any of my other rentals.

(Market price may be even higher). 

If market research indicates a particular area is losing jobs faster than the national average, has a low population rate to begin with, and has a higher proportion of owners to renters, along with other indicators of potential issues, then I may be able to reasonably assume that it will be more difficult to find good tenants, more difficult to charge market rents, etc.

In that case, my suspected property would not have to be compared to the other rentals and would be able to be compared to SFR that sell for higher.