"Rare" is relative... in my case at the time (2004), I searched eBay for a couple of months, and searched the stateside Amiga dealers' websites (which some people may also consider "rare"), and only found this SCSI module at one place. Once I purchased it, it disappeared from their listing.
Now for someone who looks up Amiga stuff everyday, they might see ten of these with no effort. But for me, I looked for a while for this thing... and if it took me that long to find just the one, I'd consider it "rare". :-)
Thanks for looking, though.
- Geoff