It was originally a $4,000USD camera. Your issue is kind of like buying a Lamborghini Gallardo, then being shocked that you need to use a special formulation synthetic oil. It's $27.
So? It is a piece of plastic worth about $.10. The price you pay for the camera has little bearing on the price you pay for a little replacement piece. Each purchase stands on its own merit. Manufacturers like how you think, it means they make even more money from you. Also, there is nothing wrong with asking around to see if you can get it cheaper, like perhaps for 1/5 that cost, which is what happened here.
Your analogy holds no merit either. A better analogy would be that the oil cap on the valve cover was lost and they wanted to charge you $150 for that, when you could have gotten for $30 by just asking around.