Definitely a nostalgic factor and what the current market demands are. As someone who grew up with a pair, they are a high gamble today, as components , even high end ones, deteriorate and become compromised over time. 10k new or used with more reliable modern design would get one comparable or superior sound. And although the market plays a part, sellers only have to find one buyer, so they can essentially ask whatever they want. Plus unless you can find a local pair, shipping is expensive, and also brings it fair share of potential problems. However, audiophiles are insecure folks, who in search of the holy grail, often remove common sense, and often make rash "I have to have it" decisions.
