This is an interesting discussion. Like many other members on this forum, I fall into both the nostalgic player + the semi-nutty collector categories. If you look at PC Genjin 3, even in Japan now the local store prices are not that cheap. Do a quick look on Yahoo JP auction, and you'll also see the game is not that easy to find. Combine the fact it is actually a pretty entertaining game (in my opinion better than Bonk 1 or Bonk 2), if you can grab it for $30, by all means get it. You have nothing to lose except $30 greenbacks, which is worth less and less by the day as JP Yen is now kicking our ass at 87 yen to $1 USD! (when I worked in Tokyo back in 2006, and getting paid in yen, it was costing me freakin 120 yen to get $1 USD! I shoulda bought more PCE games back then.. .
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My general rule of thumb is to get the best version of the games I want to play/collect... and if there are huge price differences but little to no gameplay variations (i.e. Bonk 3 US v.s. PC Genjin 3), than getting the latter is a no brainer.
Magical Chase PCE version is very rare by itself, with or without the US effect... so I can't really draw parallels to that.
Flip-flopped, SplatterHouse PCE version is clearly much more desirable/harder to get these days compared to the TG version. That's what makes life fun... we have choices... now I need to go on debating whether or not to drop $2000 for US version of Magical Chase or be happy with my hard-to-find PCE Fan version of th ePCE Magical Chase.. (just kidding, I'm perfectly content.. haha)