Very true about the subjective nature of "rarity".
I remember one time a Japanese TF saw my collection for the first - he was absolutely
gobsmacked by toys that I didn't think were all that special like the 1988 Targetmasters (e.g. Scoop, Quake, Spinister etc.) and the 1989 Pretenders (e.g. Bludgeon, Pincher, Double header etc.) -- because they're all toys that never came out in Japan, so from a Japanese collector's POV they're rarities.
Then when I brought him to dirge's place, he completely
ignored Japanese G1 toys like Lio Kaiser, Landcross etc. and went straight for "mundane" (from our POV) toys like the Triggerbots and Triggercons etc., again, all the toys that Japan never got! He couldn't have cared less for those Japanese G1 toys!
