I'm not sure that the GT430 or GT430 sport really is GT3 price though. Speccing up a GT430 sport to my taste was circa £110k. Having just done the same for a GT3, without going mad on anything cosmetic, I was coming in at £130k. Even a specced up GTS was coming in at £116k.
Throw into the mix that there's not exactly a lot of other manual sports cars out there at this level, the relative exclusivity of the GT430 and the potential of a 50/50 finance deal (if this is available) and it looks pretty tempting to me. Granted not everyone will see it this way though.