Cable Economics

Why is it that adding a five-dollar Bluetooth chip to a $40 keyboard boosts the price to $75?

Sure, there are software costs, beyond just the silicon, to adding Bluetooth support to a device. But I still think this is the wireless version of "cable economics." Go to your local big-box retailer and try to find any cable at all selling for less than $20. It doesn't matter if the cable cost ten cents to manufacture; the fact is that you're using it to connect two devices that each cost hundreds or thousands of dollars, so chances are you can afford to pay the premium.