May the odds be ever in your favor. 

Seems odd to need to spend 100k when the place is occupied and not in the worst shape.

If you are looking to tap into equity of an existing rental property, your best bet is either cash out refi using DSCR loan or 2nd equity loan.

If you're at a loss and paying off the shortage still puts you at a loss I think your best bet is selling, or seeing how you can get more income from current rents by making it mid term/seasonal or an air bnb. 

The reason we ask is because tax sale can be risky and odd things can happen. 

If I have a buyer client who has contractually agreed to whatever fee we discussed, and they are interested in an off market property, you bet I will attempt to save my client money by negotiating all or some of my compensation from the seller. 

I find it odd as the property requires inspection every 3 years and no one else has mentioned this before. 

The pricing for this one is a little odd, at $29/month or $144/year.

This is very odd especially if there was no deposit and work was performed .

The numbers on the deal are below:-$6100 PITI (5% down owner occupied)-$2600-$2800 monthly rent per unit-Off market deal near Richardson High School-Both units fully renovatedI would essentially be betting on the long term appreciation of the DFW real estate market as well as long term rent growth.