G'day,
In the 'weight reduction stakes', the best bang for your buck is spent on those items of 'rotating mass'. What that means is that you will get twice the weight benefit on any item that rotates on your bike. Ie: save 100g get 200g in 'actual' benefit. Therefore, the things to look at 1st (I'm assuming your budget isn't unlimited) will be Wheels, pedals, shoes, cranks etc......To paraphrase a line from the originally 'Mad max' movie....weight is just a matter of $$$$...how light do you wanna go?",
cheers,
Hitchy