I made a bet with my son this morning (before listening to the podcast) about lyrics to a song.

so the challenge will be finding anything that will fit into the formula. especially just a cosmetic fixer.. 

Is a good purchase price $80,000 (1%/unit) or $320,000 (1% of total rent from 4 doors)ok 80k is a much better price but which formula are you referring to

And I totally think you should be the one to create a BiggerPockets intro song for the @Brandon Turner podcast. :-)

I liked that DealCheck automatically determines rental estimate and calculates a cap rate based on assumptions I provided...and it normally gets relatively close to the cap rate I get when using my Excel sheets and formula.

I know some of it could be due to new folks that perhaps don't have their numbers right but I'm wondering if the formula should change depending on ARV?

Apply this formula to all the sold comps of similar size, plot them, and look for areas where the profitable properties are in groups. 

Running comps is more art than science and there is no single formula to adjust upwards or downwards as every market has its own norms and the same can be said for sub-markets within that market. 

Is there a formula for budgeting for preventative maintenance and repairs.

You can use the same formula, but a REI is more "mobile".Second mistake, is you are not comparing apples to apples in the overall comparison here.