> just grow a perfectly normal (i.e. full brain development) human and harvest them anyway. If you're rich through (say) organized crime already, what's the difference when it's your life at stake?

True. If you throw ethics out the window and accept murder, then "immortality" may be possible with today's technology. Probably you run into problems with mutations eventually, but you could throw more bodies at the problem and use a selection process.

You'd think someone would be attempting this in mice.