The 458's on PH are of course, speculators, hence the mark up over list.
My point, which you keep missing, is that to upgrade to a 458 TODAY and NOT in 12 months etc, is at least £120k as there are no unsold 458's sitting on dealer forecorts at list price. Of course there is the odd cancellations of orders etc but these will be few and far between with dealers only recieving a few cars themselves, plus the chances for it to be in the exact spec you would want would pretty slim. Also, anyone passing on their order will still lump on a premium, as probably will the dealer, therefore the price is likely to be list plus at least £15k.....