I got my Mark III in a trade, which I would value at well south of the price you saw. I've seen a few used BHPs at around $700, but they were in nicer shape than what you mentioned.
BTW, a friend of mine has one of the Argentine clones. It shoots well enough, but I recall the trigger being gritty, and the overall feel wasn't as good. But he didn't pay that much for it.
"An armed society is a polite society." — Robert A. Heinlein
"After a shooting spree, they always want to take the guns away from the people who didn't do it. I sure as hell wouldn't want to live in a society where the only people allowed guns are the police and the military."
— William S. Burroughs