Your best bet when it comes to finding good, quality advice is to solicit it from people who are making it happen in your geographical area since REI is so local.  

Surely, to build a NEW same-quality home there shouldn't cost $400k+?

Just to underscore @Mike Dymski point; I recently met with a contractor in Ohio who took me to another site they were working on to show the quality of work.

Buy good quality rentals with solid cash flow.

And please keep in mind that your ability to sleep well at night and your quality of life might be worth more than making a few extra bucks.   

I have had great luck with finding quality tenants in about 10 days. 

You want the turnkey provider to own the management company so they are incentivized to place quality tenants or it's them who deal with the headaches.

It has the most complaints on quality. 

Also keep in mind rural usually means lower quality tenant pool and guaranteed higher vacancy rates.What are your vacancy/eviction estimates and legal, advertising, accountant, utilities while vacant, office, vehicle etc. 

The consensus is that different types will generate different response rates and differing quality of leads.For example, apparently yellow letters generate a large volume of phone calls, but low quality leads.