And often the improvements to be made are raising rents to market.

Took this over from original owners at severe under market rents.

Additional Information:Any advice on navigating a market move with ongoing investments would be greatly appreciated!

Contacted and agent from Zillow in the Austin, Texas market and they suggested the area.

I'm talking to a few about eventually looking at long term rentals as the STR market seems to be pricing the locals out of the buying market.  

There is a possibility I can get 3 houses for under 10k each but they aren't for sale and I would have to direct market to the owners.

Go to Etsy and search for "rental property tracker," and you will find hundreds of nice spreadsheets to track 10-20 rentals, usually for under $10.Software has extremely helpful features like online payments, marketing syndication (click a button, and your property is advertised on multiple sites), electronic document review/signing, maintenance tracking, and owner reports.

I am marketing toward Subject To prospects and I have never seen this particular topic regarding refinancing sub to brought up before.

Does anyone have suggestions of locations to look at that are decent to live in, have a good rental market, and have available properties that are reasonably priced?

There are "rules of thumb" to operate by, but they are general guides that change with time and definitely change with markets.