Typically buying them between $10K-$20K which means you would need to pick them up for less than that to make a profit.

Very clearly define the profit split in the GMP contract.

We look for owners who want to sell their land below mkt and we get there first and make a profit buy selling it well priced and quickly.

Therefore, it would not really have been a $20K profit.  

He said it was impossible for the other players to catch up to him because they simply did not have enough time.

Also, there is more to the deal then simply negotiating the deal - make sure you understand all aspects of the closing process if you attempt this without an agent (from inspections, to objections/clauses to get you out, to on record and off record title work, just make sure you know the full process which is what a buyer's agent can help with).

But hired professionals for things like plumbing ($6100), AC/Heating ($15,000), electrical ($2000) and landscaping ($5000) All profit each month is directly applied to the principle.

I've been an RN for 7 years and in between patients (living and dead) the rooms are simply washed down with either bleach or alternative disinfectants, day after day after day. 

Your 121 exemption would only apply to the gain/profit on the last transaction....all prior deferred gain would become taxable.

I was tempted to post here asking simply for direct advice on my situation.