My husband and I have been 'casual' landlords for a few years, and now I'm putting together a business plan and am wondering if anyone can suggest software that might be helpful. 

When I started out, I avoided using too much money on paying for real estate softwares and such as I rather invest my money on deals first.On the flip side of this, it has somehow caused a little bit of a mess in my business.

It is often also referred to as MAO - Maximum Allowable Offer.In all of my analysis I always use the MPP/MAO procedure since I have this automated in the custom software that I have built for myself.

After going through some automation I was able to talk to a lady who told me, that they are the mortgage holder, but are not the owner, and could not sell me the property.

We are evaluating property management systems (123landord, Rentec, Buildium, etc) to manage our single family rentals.  Currently we are using Excel but we'd like to find something more efficient.  The problem we have...

Is there a good software to find these deals?

The distribution center is mostly automated so the people working there are six figure salary.  

On average, agents gather criteria specified by you and then you'll receive automated messages for properties fitting your criteria. 

Also, is there any free or low cost software that is similar to proptrend?

Freedom Soft is a good software to have for pulling lists.For more targeted lists you can create and purchase a list on www.listsource.com