I know it's fun to hate on $INDUSTRY, but lets get down to the technology here, the science, and what is possible today that wasn't possible five years ago. We can argue about the costs later, it fundamentally doesn't matter. No single person will pay $850K for this treatment, it'll be insurance, charity, etc.
What has been developed is a virus that introduces DNA into specific regions of the body. It's really mind-blowing! Think of the possibilities this opens into other treatments. We may be able to adapt the science heal lungs in those born with cystic fibrosis, repair hearts of children born with cardiomyopathy, cure Type I/II diabetes, etc.
Besides, if Toyota had to build only as many cars, as patients received this treatment, those would cost a million bucks too! The price seems reasonable for the amount of work that was surely required.