Will your model assume cash or mortgage finance? Mortgage comparisons can alter both timing and total cost, so one financing assumption may make cross-market results look more comparable than they really are. You could run a cash case first, then add financing scenarios without allowing them to...
I wouldn’t give too much weight to a refinance assumption. Future rates, valuation and eligibility are unknown, so a quote that looks attractive only because the model assumes an easy refinance may be misleading. Test whether the monthly payment remains comfortable without refinancing, and ask...