mmm...parts list....
well i dont know what's too expensive for you but id would do...
thomson seatpost and stem(obvious choice to me is the 1 1/8" headtube)
Velocity Aeroheads(great weight/price ratio)..my wheels are these laced 32h Rear and 28h Front to Dura Ace low flange..but if u dont want to spend that then formula i guess
Miche cranks and BB or Campy road BB if you feel like the upgrade
Eggbeaters if you're commuting on it
that's all i've got