E-Bay only gives a brief snapshot of auction history.
I don't think I saw a single 50[sup]th[/sup] Anniversary set for under $2000 last year, but that is from occasional browsing. Perhaps there was a pyramid effect of people buying NOS sets, marking them up by $1000 and attempting to sell them again.
There do seem to be quite a few sets floating around at the moment.
Looking at the individual component sale history on E-Bay, I think they come up to a little over $2000.