In my area you can be 25K off on the same age, style, sq. ft. and school district not knowing the neighborhood yet still be within 3 miles of the subject.Tons of information here on appraisal issues, search "appraisal comps" and you should get plenty of reading.It's not just math.

After shooting them down a few times with numbers and basic math, it's a lot easier now.

If you have done your homework regarding clear title and can pay off the mortgage perhaps a subject to, could work but my experience is that distressed homeowners are often over a year in arrears with taxes , insurance and penalties building and this will add significantly to the cost to pay off the current mortgage.

But you did ask to take the wind out of your sails, so that's why I mentioned someone already tried a similar purchase and it was denied, so make sure you do your homework with the loan officer before you commit to a purchase and it falls apart at the last minute.I truly do believe though that they will not see it as a primary residence if you are only in the ANG for one weekend a month, and the rest of your time is spent going to school .

The math is the same.Again, when you do the work yourself, the most money you're saving is $50/hour (in theory -- I actually can't think of any contractors I pay $50/hour to).

Do the math on your investments, then do it again!

How did this math work out?

The math looks good to me, and I plan on putting 20% down and financing the rest in a conventional loan.

You have to prove that you've done your homework which may or may not involve taking some sort of formal training/education. 

Doing my homework is my first homework assignment.