Originally Posted by spare_wheel

Tiagra SL-4600 shifter: ~$105
Ultegra 6650 compact crank: ~$139 at Jenson (a 5650 or 5750 would be fine too)
Ultegra 6700 derailleurs: ~$125
KMC 10 speed chain: ~$20

If you go all 105 you could knock about $50 off the total but, IMO, ultegra is better price performance.