On the pricing front. I've designed systems which use the RPi as a base and are sold for several hundred pounds (spectrometers).
The reason is basically margin and not going out of business. If you want to make any money, you need to sell at around 3x your BOM cost to compensate for distribution, optional sales events, labour, amortised certification costs and so on.
Working backwards, $250 means about $85 in parts. A custom printed DIN rail case probably costs $15-20 in small volume, the Pi is $45 and that only leaves $20 or so for the PCB and components which seems easy enough if they've over-specced it for industry. I wouldn't be surprised if this thing costs $100 to build; not including labour, packaging and shipping.
This is a classic "I'm an engineer and could build this for 1/3 the price" - sure you could. But you couldn't sell it that cheaply and make a business out of it.
Doesn't sound like he's saying that. Sounds like he is saying the $35 model will work just fine. And it is already proven and produced on a mass scale.
This is an extension kit to a well designed and well adopted embedded system. The OPs complaints to me read as: nobody wants these features because the stock model works for OP, and that the price was jacked up to cater to an industrial market. I addressed the second point above - to stay in business, hardware costs money.
On the first point, the product definitely provides benefits over the stock Pi. If you need those improvements, you need them. The $35 model will die if you plug in a logic level that isn't 3V3. It certainly won't handle standard RS-232. It doesn't have a proper power jack - either USB Micro or two GPIO pins (no latching). It also doesn't come with a DIN rail mounting system, nor an RTC, nor a UPS, nor a good voltage regulator. Some people might want those features (I've worked jobs where they would have been useful.)
Also on the buzzer front - not all DIN boxes are in factories. They're used inside buildings for power distribution and fuses, in greenhouses to control irrigation systems. These aren't necessarily noisy environments.
The reason is basically margin and not going out of business. If you want to make any money, you need to sell at around 3x your BOM cost to compensate for distribution, optional sales events, labour, amortised certification costs and so on.
Working backwards, $250 means about $85 in parts. A custom printed DIN rail case probably costs $15-20 in small volume, the Pi is $45 and that only leaves $20 or so for the PCB and components which seems easy enough if they've over-specced it for industry. I wouldn't be surprised if this thing costs $100 to build; not including labour, packaging and shipping.
This is a classic "I'm an engineer and could build this for 1/3 the price" - sure you could. But you couldn't sell it that cheaply and make a business out of it.