A 1970's cure was to dig out around all the basement walls coat them with a 1.5 inch layer of tar to seal it up.

It might be a good bench mark for me to know whats realistic Sorry I haven't been on here in a while nor answered your question.Well in my market rentals go for $160-300k/ unit depending on the submarket and if it's a newer build, value-add or rehab.So it's very difficult to say and it depends on your own personal finances.But for buy and hold I've purchased 22 units in 2016, 6 units in 2017, and a few in 2018 and 12 u in 2019 Some were local Los Angeles County and some are in SE Florida.I also sold several properties in LA last year, some were hybrid hold/flips and more development deals...Also asking how many units could be completely different in a market like OKC or Utah where you can likely get units cheaper, OR the market might not have larger apartments, unless it's in a larger metro like Salt Lake.. so it really depends. 

Check the foundation walls for cracks and seal them.

I'm taking the experts opinion with a grain of salt and articles like this are laughable....This.Basically, anything that the experts are predicting, etc., take with a grain of salt.

So take that with a grain of salt.  

Paint throughout Added closet to make an official 2 bedroomRemoved 1 tree out front that was ruining drivewayAdded dishwasherPoured back patioAdded storage to laundry roomNew flooring throughout Remodeled BathroomNew doors, fixturesNew GE Slate AppliancesPoured new sidewalk out front, sealed foundation, fixed front patioWhat was the Outcome?

As stated above, most contractors won’t do a cost plus structure, but it is fair to say that you will be paying 20% or more beyond what it would cost if you GC yourself.Also, I can understand and appreciate the good intentions behind @Mitchell Zoll’s advice, however most contractors worth their salt will turn around and walk away (likely laughing) from a request like that.

I'm looking for out of state properties to invest in the 50-100k range and have come across places like Detroit, Salt Lake City and Cape Coral Florida.

I've build my portfolio and retired from the W2 by taking rules with a grain of salt.

However, remember that these are commissioned sales people who want to sell you a property -- take their advice with a grain of salt.