I can't speak for everyone, but I can cite several reasons why I'm always more conscious of picking them up: - Early exposure: A lot of us used DEC systems in college. If we've stuck with the field, we probably have good memories of that time, and when you start getting to a certain point, the nostalgia connecting you back to a happier time is worth a few bucks. - Availability: While we'd all love to get our hands on a straight-8 or a PDP-7, there are certainly a number of models that are quite plentiful. So newcomers to the hobby can get their feet wet with with something outside the 8-bit world pretty easily. - Available software: Partly because of the availiability of the hardware, there's a lot of software out there. So when you get one up and running, you generally can do more than look at the blinkin' lights (though that's worthwhile in itself--much more soothing that a lot of other things). - Company history: The history of the company is long enough to be rich and short enough to be an object lesson. Because of that, the machines are connected with an important element of the overall history of the comuter industry. - Interesting machines: As you pointed out, there're often quite interesting machines. There's a good collection of documentation out there both in terms of details of specific models and in terms of the evolution of the families. - Connection to other history: Because they were so widely deployed, they're associated with a number of other historic bits of computing history. UNIX may be the most obvious example. Anyway, those are a few that come to mind at the moment. BLS