Love them myself was just about to buy one as my next car until circumstances changed meaning I need a stupid jeep instead.

How come you've ruled out the 645i though? Honestly not that much worse to maintain, run etc than the 30i ( by all accounts) and the only unique issue they seem to have is a poorly placed water pipe that's easily rectified. For the power and more importantly sound, I'd really go for it, the 650i is more powerful again and a tad newer too.