There is a whole pile of fantastic cash cows like this in aviation...
You can say that again. For one example, about
these standby alternators
2200 US$ for a bloody alternator turning out a measly 20 Amps, plus another 435 for the installation kit. Even if we're in aviation and the volumes are small and whatever not, this seems quite exaggerated. And if the engine quits, you'll still have to rely on what's left in your battery.