I was in the US Air Force for 6 years, then went through some trying times after I got out and had to basically rebuild my life from the bottom up. 

It was about $600 in permits, $800 in utility kill (assuming you're going to rebuild there and Class A street work is completed in your rebuild), and $12000 in labor and dump fees.This was for raised foundation (cheaper than slab), no garage, very accessible lot for working space, urban location (less hauling distance), and taking advantage of recycling credits for C&D waste. 

They intend to rehab/rebuild all of them to the same standard.

If your properties are concentrated in one area or state you could be facing the rebuilding costs for multiple locations and the loss of rents for those same properties all at the same time.You may want to have your agent look into a policy on all the properties with a very high deductible and see how that cost would impact your plans. 

The three main valuation approaches are sales comparable (based on recent sales), income approach (based on the NOI and market cap rate) and cost approach (based on cost to replace/rebuild  the property from scratch).GRM, gross rent multiplier, is the number of years the property would take to pay for itself based on the gross potential rent.

He recommends that we go for a fast sale for $125,000 to a builder that will tear down and rebuild.

Most of the major business in that area will probably just rebuild - Target, etc.

I want a shelter with acres of property for all types of rescued animals and I would love to travel the world with all the generated income from real estate to help rebuild communities and rescue animals! 

It is unlikely that you will try to rebuild a building in south city.

I toured the property and it needs a full gut and rebuild.