@Glen Beringer is right that on his higher end rental he wont need to set aside 10% because he's charging 75% more in rent to cover the same fixed cost. 

It's one thing to help mom out by charging under-market rent.  

I used rentometer to determine rental prices, but they charge after 10 searches. 

Is my best bet to find some comps and submit those?

What's else should I bet looking for for?

Hobby landlords that charge below market are the type of landlords we are all seeking to buy from.You will likely need a GC to do an evaluation on repair costs.

Obviously in Houston most would prefer a large home for that price, but there are still plenty that prefer condo lifestyle with no home headaches but there's one for sale right now over $5M in my building a little bigger3) David -  Like I mentioned mine is many floors higher as a comp that sold a few months back that was basically stock from the developer, mine is upgraded significantly and higher, but of course that's irrelevant now as that one sold at the time and ours has not.There's really no rhyme or reason in this end of the market, I don't expect a quick sale from my realtor but it has been nearly a year, at some point you just begin to blame the person in charge of selling it for not marketing it properly,etc.

But long term, by carrying your mortgage for the full term and making minimum payment, you are racking up some serious interest charges (but hey that's finance folks).It really depends on your financial goals and what YOU want.  

The answer is that that is the only politically acceptable way to do it without charges of bias, profiteering, discrimination, etc.Ironically, the wholesalers are doing what the real estate broker can not do, using a net listing, pricing the product individually by time, effort and demand.  

In fact, it will increase your taxes by lowering your interest deductions as you pay down principal and reduce interest charges.