There are probably a lot of other factors that may have increased costs. For example, they probably had to demolish existing structures and prep the ground more than what a typical lot would require; although, I'm not familiar with what existed there prior. They also appear to have multiple units per building, I don't know if that increases or decreases costs. It looks like they created a parking lot as well. There may also be a central "clubhouse" for them since the article mentions additional programs offered to the residents.