How to get fair comps for small houses?

[Dwayne Jones]

I’m a builder/developer in Memphis, Tennessee trying to rebuild the inner city. Currently we have several vacant lots via individuals, land bank, and tax sale. I have one bedroom and two bedroom cottage home plans for sale with a lot of people interested in purchasing. The houses range from 280 sq. ft. to 832 sq. ft. Low income, service workers, millennials, live in place etc. I have two models (both 480 sq. ft. one bedroom one bath) 90% complete but there hasn’t been any new construction in the area for years. Before I started construction I tried to get an appraisal based on plans and specs but no appraisal would give me a value for a new 480 sq. ft. home in the inner city. The cost of new construction is what it is and shouldn’t be compared with existing houses. They also have an issue with using larger new home values in other neighborhoods. Any suggestions on creating fair comps?