In my view the time spent on sourcing, ordering and installing lighter components assists speed far less than would spending the same time on the bike. In addition, wearing better fitting clothing would probably offer more benefit at speed. Taping your shoelaces saves .8% at only 22 mph and shoe covers 1.4%, which is more than you will gain with even a 1 lb decrease in weight.
http://sheldonbrown.com/rinard/aero/aerodynamics.htm

Remember that not only is weight less a factor (except when climbing) but that you have to add your own weight to the bike to evaluate how much you are saving. So my opinion would be that the bb cost would not be worth the money. A better use of your money might be to get professional fitting or coaching.