The Porsche/Audi idea of having the valet key encryption limit speed and RPM sounds like a good one, and I would agree that it's worth more than $10. Regarding sophisticated anti theft measures that make a car key cost over $100.00, first, if an accomplished car thief wants your car, he'll get it regardless of what type of key it uses. Second, is there any statistical proof that encrypted keys are any more effective at preventing theft that a simple steering wheel club? And what's going to happen when the sophisticated anti theft system is ten years old? Will the key still work? Will the car start when it's supposed to? I know that manufacturers always say that gadgets of this type are foolproof, but that never seems to be the case when the car is a few years old. Ask anyone who has an S-class with power door closers. The two people I know who have this system on their cars have had to spend large amounts of money to have pumps, etc. replaced. And who do you know that is breathing, but is incapable of slamming a door hard enough to close it all the way? While I agree that technology is a wonderful thing, gadgetry is not, and only makes for more trouble and expense.
Colin