This house is smaller, 2br 1 ba 940sqft, and i was looking to add space for another br/ba ~300 sqft??

Okay, go to your local public library.

I'm also aware property records are publicly searchable (if you know where to search, that is).

A small example of this was the very first rental I got was already in decent shape, but I really went through and updated it as well as added a permitted bed/bath combo in some existing unused open space (if you can't do the work yourself or don't have a trustworthy contractor, it makes a lot less fiscal sense).

Why is a half bath & a bit more space worth 40k more than a 2 car garage, for example?

Even if you lose, the fact that you filed suit is now public record for anybody who cares to check public records for this.

Unfortunately the downs are the fees, you will have to have a broker and you'll need to make sure he's investor friendly, you will be held to a higher standard because you'll have t follow the code of ethics and responsibilities to the public.

Not one email complaining about the space.

Is this information available to the public?

If you're interested in learning on a grader scale there are commercial sites and publications.