This should give you a cap rate average.So you have your all in (cap rate to cost) whatever that is and then your market cap rate say 6.5.

Should I base my sale price on the 1% rule, NOI, or a CAP rate?

The calculator I'm using shows a Cap Rate of 18.5% and cash-on-cash return of 40.9%.   

When I see a cap rate that high, I tend to be suspicious that it wasn't calculated correctly.

I’d do a quick google search on what a cap rate is.

I try to offer a price at a cap rate higher than the current market which just means a lower purchase price which I think 99% of people on here would do the same.

Once you understand the power of a cap rate, owning apartments are better than homes (1 to 4 units). 

I've been structuring the deal with a cap of 75% on both the purchase and rennovation costs, now it seems I could potentially offer the seller 25K more in the offer, making it much more likely she will go for it.Alas, the more I consider, a HML may not be the best way to approach this deal, but I will offer it to her just in case she want money in her pocket before any title work is done.George thank you!

I'm not sure how to factor in a cap ex into ROI.

A portfolio loan for rental properties wouldn't be affected by a cap on the personal mortgage interest deduction.