Estimates for cost are extremely rough. It would take a detailed plan of what would be going into this building to determine more exact figures, but luckily educated guesses are very often astonishingly close.
- The cost per unit for an apartment would be roughly $86,000. This would put the total estimated cost for the building at $100M, including overhead and the fact that we’d be using more environmentally friendly building techniques. 
- A 56,000 square foot two story mall has an estimated cost of $25M. Since building up generally costs less than building out, it is reasonable to use $50M as a high ball estimate for the shopping mall section. 
- A 115 room hotel with en suite amenities, a common lobby, and facilities for 24 hour room service would run about $22.2M 
- Since we already know that a 56,000 square foot two story mall would cost about $25M, it isn’t unreasonable to use this estimate for the commercial/industrial section.
- The cost of 1,500 acres would vary greatly by region, but in total would only come to about $15M – $25M for land that would be best suited to the project.
- Sewage Treatment
- The sewage treatment plant seems to be the one largest expense, but that’s because it’s designed to handle the entire water footprint of the 2,400 residents and 230 guests. The Brightwater treatment plant handles, on average, 36 million gallons of waste per day. That’s almost seven times the amount needed for this project. Of course, economy of scale comes into play so the cost will be more than 1/7th the cost of the Brightwater plant. Figure about 1/5th the cost. That would result in a cost estimate of $360M. 
- Solar energy production has an estimated cost of about $5,300 per kilowatt, but this wouldn’t include the use of novel technologies to capture emissions which would be necessary since we’re using biofuel as one possibility in this case study. Assuming a cost of $6,000 per kW the total cost would be roughly . A 17 MW power plant therefore would cost roughly $102M, making it the single most expensive component of this project ** (Figured changed making sewage treatment the most expensive). This does not include the cost of actually obtaining fuel and operating the plant.
More estimates will be added in the figure and hopefully a more detailed analysis of what is needed will be available as people decide to take interest in this project. Of course, there is also the possibility of converting an already existing mall which has gone out of business into a test platform city building. Of course, the odds of it having the necessary land to be self sufficient are next to zero, so it would be an even smaller prototype than the one imagined here.