I decided to get my license and according to the math I will break even on the board of realtors fees if I do one deal per year.

Live with parents, get your cost of living down to like 15k a year (no housing payments, no car payments, and make 65k/year,  then the math works).  

Make sure you double check their math, I have caught mistakes before.

Like a broken record, the trick is to find out the perfect Location, Location, Location ;-) Many STRs break even or even lose money because the math needs to make sense in terms of year-round high average occupancy rates necessary to pass the break-even threshold.

The primary reason is I'm having a hard time following your math, the numbers given don't really line up - I'll get to that in a moment.

From looking at your math evaluation, it does not look very good. 

So a math example would be: buy for $100,000, spend $20,000 fixing it up, sell for $150,000, pay taxes on $30,000.

My goal (considering TVM principles) to get my money back within 5-10 years and for net present value to be better than selling and putting the cash in a conservative portfolio of stocks/bonds - which would be for me: 25% stocks/65% diversified bonds/10% cash or something of that nature yielding 3-4% after tax.My challenge still.... is the math and comparative analysis with different seller financing structuring. 

If you don't have a firm answer you may never buy a primary residence because the math will always tell you to invest more. 

It comes down to the math.