It is rare.
While 5 times as many E3 were built compare to the E9, far less have survived. That´s because, while a great and impotant car (for BMW), the E3 is is hugely underapreciated and thus undervalued.
best guess as to current survival number is, that for every still roadworthy E3 there are 2-3 roadworthy E9s still around. I´d call that rare....
Some say, the E3 is the steal of the BMW world, but unfortunately that´s not true. While the survivors can be picked up pretty cheaply, hardly any E3 has had money spent on them and thus, you´ll be fixing and replacing stuff all the time if you actually drive such a thing. Those mad enough to have actually spent some $ on their E3 then usually keep them (since you´ll never recoup), thus all E3 that ever come to market are close to scrap, thus their perception is that of a junker and so on. It really is a viscious circle....
Ask me how I know all that :lol: