Rare doesn't mean desirable.
There were about 400 games produced with under 1,000 units over the years (but excluding games with say 15 or less to exclude pure proto/non-production games).
ESB is rare by number count but generally not sought after. It's common here because they were produced here. Rare but not desirable.
Gottlieb Spirit is rare as games of it's vintage go (about 1,000 produced) and due to the unreliability of the board set, the survival rate would mean a much lower number, so this is both rare and desirable.
Similarly, Asteroid Annie was a low production and probably low survival too, produced apparently to use up board sets, so a low number despite being quite a decent player, so this is also both rare and desirable.
Then you have games like BBB, very desirable and very low numbers due to particular circumstances (about 200 all up of protos and "production") - very rare and very desirable.
Than again, rare in context of the hobby - I have owned all four games, so just how rare is rare? Shows what a niche market pinball is.