Good , no breaks , probably a broken water main , called the neighbors and they had water .

Are you planning just to shine-up all the units and get them rented immediately or will you conduct a deeper renovation and upgrade the building envelope, windows, etc as you turn over the worst units?

The property has been on the market for over 100 days now, and I'm concerned that I might have a hard time selling it after 5 or 10 years if I decided to upgrade.399,000 is the list price.

It's the second, if not first by now, market in Oklahoma, specifically the Owasso, Broken Arrow, and Bixby areas.

However, if you can get more rent for upgrading your unit, why not?

Not to mention we were able to do some very nice upgrades to our side of the duplex.

There is an aluminum screen door,  then the broken door in photo leading to a 3-seasons room type enclosed poarch. 

Shards of broken glass every where.

I know this answer could be a HUGE range depending on the upgrades we install on the interior but any information would be very helpful.  

There are good tenants even at low incomes so as you convert/upgrade  make sure you get the cream of the crop in all units. kick out those lease violators.