@Doppie1200
I even saw someone claiming that the PowerFlyer ZIV was a rare item; an item which still can be bought! Furthermore I saw an Amiga 500 advertised as rare because the hdd that followed the A500 was a 550 MB one...
The only items you can classify as rare IMHO is stuff like prototypes, special boards as the AmiJoe card for A1200, Viper/Apollo 630, Bodega Bay, etc.