Oh, there are > 100000 unsold / unbinned Amigas yet. What % of those will actually go on sale is anyone's guess... but the trend so far is that most try a sale before binning, and most ones on sale get sold. So I don't actually see A500/A600/A1200 going rare very soon. Still plenty of CD32s available for basically everyone that wants them.
The other models are much more rare already, although I can't really say it requires more than a month or so of patience to find one. But that's with Amibay.com etc, with ex-collectors selling off spare ones. THAT kind of thing might trickle down in a few years.
What is also getting rare is expansions - but Jens Schönfeld is fixing that right up! We should hire bodyguards, what if something should happen to him