I think the FBI messed up on several levels here. When Apple said (not publicly) they wouldn't make the back door the FBI should have found another way in and not told us or Apple about it. Apple would infer that they figured out another way in when they told all of us they got in, but there would have been no big publicity thing that - it seems to me - the FBI lost.
Also, before the announcement about hiring the Israelis to do it for $15K I had been placing the cost to break into an iPhone around $60K to $100K to decap the chips and read stuff out with an electron microscope. I still wonder if my estimate is about right for the decap method and the Israelis just know a shortcut that makes it cheaper.