Rare is a relative understanding. If I'd ask 1000 people if they have an apollo scsi addon 1 might say he/she does.
So from that point of view it is rare.
If you want something and it takes you 5 years to find it. It also is rare.
This example does match the first point of view. It is however very easy to get. In fact, I have one my self but I am to lazy to put it up for sale
