Many “wholesalers” get all excited when getting a property under contract only to discover that a thorough inspection by a knowledgable professional results in repair costs 2 - 3 times higher than they calculated. 

The total appreciation of $172,500, assuming an average annual return of 4.3% over 30 years, would be approximately $609,984. curious why the last calculation is using a rate of 4.3%? 

The properties have unique advantages accruable to an investor who is willing to do their homework and take calculated risks.

My conclusion is that take the provided ROI calculations from REI as purely estimates.

Will they base their calculations solely on the income from the two legal units and disregard the non-conforming basement?

Additionally, I would suggest you run some financial calculations such as cash on cash return as well as any appreciation from the asset if/when you sell.

Finally, BP has various tools available to help you analyze your deals (rental, flips, wholesale, etc), feel free to use them: https://www.biggerpockets.com/investment-calculators Please let me know if I can help, and best of luck!

Sometimes, different lenders have different approaches to rental income calculations!

One thing thats hard to calculate is rent growth.

Were you making a calculated decision?