You can get comps from neighboring buildings, but they might be newer builds or have nicer features which justify their higher price and an agent would need to help you if your unit would command a similar price at this very point in time.

It's my hope that I might be able to find a property with cheap taxes that I can make improvements on that will command higher rents.

The rents are WAY too low for how much the area would typically command.

So, a triplex in Cleveland might command $600 per unit, or about  $21,600 per year in income.

Scale it down unless it will truly command higher rent.

I could get a duplex or a more expensive 4 bedroom on the site and command more rent but for comparable construction cost the duplex would make more sense.

markets go up and down. the improvements you made should command higher rents, your realtor is not an appraiser and while she can do comps she may not fully realize the value of your improvements. 

It is therefore, ORDERED that publication be made in the GALLATIN NEWS EXAMINER a newspaper published in Sumner County, Tennessee, for four (4) consecutive weeks commanding said defendants to file an answer to the complaint with the Clerk and Master at her office in Gallatin, Sumner County, Tennessee, according to law within thirty (30) days from October 30, 2015.

Again, the property will be located just outside of Boston, so it should command solid rents (i.e. $1800-$2200/month, per unit).

You might also consider some of the bedroom communities of Sachse, Murphy, Wylie as they can have great returns and command higher rents.