With one duplex you should be focused on selling 99.9% of the time and .1% on the duplex.

I have a lot in a nice community in Gouldsborough that I have not been able to sell.

(not sure on state law but this probably is a tough sell)4.

Many are buying properties, doing minimal renovations to keep their crews busy, and selling with small or zero profit margins.Cash buyers are a priority.

Selling one and buying several is fine. 

Purchase price: $2,000 Cash invested: $60,000 Sale price: $91,000 Bought this one from WCLB with the intention to fix it and sell on market to homeowner.

Is this an offer to sell, invest, or broadcast?

Simply put, we start off with the As Repaired/Completed Value (ARV), then subtract from that number a reasonable profit, the rehab cost (scope of work), which we've gotten good at, a contingency reserve for any "unexpecteds", our cost of capital/carrying costs (interest and costs of the leverage used), and our costs/fees on the buy and sell sides of a flip.

And it can work really well for you as long as you pay attention to the statute requirements.In order to defer all tax you are selling investment real estate and buying investment real estate of at least the same value you sold. 

Keep in mind that I am selling them as affordable fixer uppers and usually only address any health, safety, and functionality issues.