Notes

principal buydown @ 30 yr amort is about 1.8%/yr. 5-yr arm rates are about 2.8%, fixed 4.1%. so with 20% down, a 7.6 cap gives a 15% coc + 9%rop for arm, 8%coc + 9%rop fixed
breakeven cash flow is 4.6 arm, 5.9 fixed

condos seem to have ~8bp/mo condo fees, 10bp/mo taxes, let's call it 7 bp/mo insurance/maintainence/misc, so its 25 bp/mo total.
But 10-12bp of those are tax-deductible, so the after-tax cost is around 20bp/mo
principal varies (18bpm @ 2.7%) and interest w/ 20% down is around 6.2 bpm per percent interest pretax, so around 4 bpm post-tax. intriguingly, this implies
interest cost only exceeds other costs at 5% interest rates. So current post-tax cost for arm is 32bpm, for fixed is 37 bpm. So an apt with a monthly
rent of 2k is, under an arm, 2000/.0032 = 625k. But that's ignoring the time-value of the ~125k we have to invest. Under a 12% return, our 20% equity is costing us 12bpm post-tax, which implies the true breakeven value is actually 2k/44bp = 450k. The flip-side is we might expect a long-term return, each point of which effectively reduces our cost by 8bpm under the assumption we are staying 2+ years and will pay no taxes. under even a modest 2% expected return, we go up to about 1k rent being equivalent to living in a 350k property.