Stick with the math and don't let emotions get involved.

I'm doing a bit of math on a potential deal, and the way it works out, I can potentially put in $80k (purchase for $60k, rehab for $15k, $5k refi closing costs), and increase the ARV to $120k.

Nathan G hit it all.... it wont be an exact match but it will get you as close as you can separate from individual meters etc.....Do the math and add some cushion as back up....

Go ahead and use for quick math when looking whether to buy or not, but it takes analysis within your market.  

My math shows I can buy one brick ranch for 90-100k, rent it for 1k/mo and collect my earnings with little headache.

Secondly, I found an article here that suggests that what starts as positive leverage through financing becomes negative leverage over time, but I'm not sure his math is correct.

Then I did the math as to when I would gain 20% equity in the property so I can refinance.

Typically the smaller the deal the points go up which on paper sounds rough, but if you do the math even at 6 points you aren't actually talking a lot of money. 

Is this math right?

1/2 of something is better than 100% of nothing.  6 mos from now you could have 1-3 deals under your belt and now ready to run 100% on your own.If you can do basic math, you're ready to go - I can buy it for "x" amount and sell it for "y" amount with "z" amount of repairs....Is there a profit there that I'm happy?