The M135i is something you'd want rather than need. With Sydney driving there is no point getting the M135i cause speed limits and traffic around here sucks.
Coming from an M135i owner (and i'm 21 years of age) if i had my way again i would have bought the 116d. The savings from the petrol, insurance, service etc would have served me better with other lifestyle buyings haha
As i recall a standard manual 125i with no options was about $45K where as a manual M135i with no options was $79K. I'd say buy the 125i with some extra little goodies (sunroof, xenons, leather seats etc) and take yourself out every now and then and get loose!