First off,

if no one has welcomed you yet. Hope you stay around
Please, dont make a fake M5!

Personally I think that M5 kit looks pretty sweet, but there are real M5's everywhere, it is nothing special. It is all a matter of opinion, I personally really like the Hamann kit and would choose that over the others and especially if money was no object. I dont know prices but it has got to be expensive, from what I have seen in Bavarian Autosports (bavauto.com) the G-power kits look pretty nice too.