If all goes well with my inspection I will be closing on a small duplex in a little over a month.

How routine are in your Inspections?

And I would contact the county inspections office to let them know what happened.

Maybe plan to have the property inspected every 6-months to ensure it's being taken care of ?   

First would be acquiring the property: Inspection cost, appraisal if financing, and then closing cost. 

An inspection may not be a bad idea to to make sure your bases are covered for major issues such as foundation, roof, mechanicals and etc. 

You can put 20% down and avoid the mortgage insurance premium (mortgage insurance for conventional has MANY choices: lender paid with higher rate/ split/ monthly.... and so forth but it is much cheaper than FHA 1.75)Home Ready may have income limits and county limits FICO 620 minimumDifferences are: cost, can you qualify, how the individual regulates your inspections which is lender specific

Driving in the neighborhood. 20k less than asking price,cash offer no inspection and closing within 4weeks.

As a home inspector, I would call this out if I was inspecting it for a buyer, but I would also look for some other signs to show the significance of the issue.

I had an inspection done and used that to negotiate it down a little.