It's like cars. Some hold their value longer and better than others. Is US$30 million too much for a used car?
Someone didn't think so. Personally, if I ever hit the lottery, I'm buying a Jaguar XK-120. I could get two brand-new cars for what I'd have to pay for a 60-year-old car with a wonky electrical system, but they're not making them anymore.
For the people who like the Sony PRS-505, there is no substitute available. Not from Sony, not from anyone. So we'll pay what we can afford to obtain one.