Push Start Ignition Switch Replacement?

I'm just wondering what it might cost to replace the ignition switch button out of warranty if the switch button "wore out" or the spring or whatever mechanism it uses to move in and out broke.
I don't mean some kind of electronic problem with the ignition or computers, just a mechanical failure of the push button switch itself.
Is the switch replaceable by itself or does it need a whole "system" replaced?
Is it more expensive or cheaper to replace than a worn out ignition key cylinder on a standard key start vehicle?

 

I don't expect to need this replaced especially since I may get a new car in a year or 2, but I am curious on how it is set up. If Toyota assumes that it will last the life of the vehicle, then it is more likely the switch button cannot be replaced and you will have to spend a huge amount of money on replacing the entire system and maybe needing all new key fobs to go with it even if the only thing broken is the switch button.

 

So the exterior button itself cannot be replaced just as a stand alone part?
Isn't there physical contact with something when you press it just like when you press the power switch on a computer? The button itself is not starting the car. Isn't it just a decorative trim piece pressing on something else behind it?