I noticed you were talking about building a new bike. After Easter, I'll have a complete Ultegra 18-speed drivetrain for sale:

Ultegra Brake/shifter units.
Crankset: Shimano Hollowtech II compact, 34-50 (I also have a regular Hollowtech 42-52 if you prefer).
9-speed chain, Ultegra
Cogset: 12-27 tooth, 9-speed Shimano, I'll have to check whether it is Ultegra or 105 quality.
Derailleurs, front and rear: Ultegra for double crankset. The front derailleur has a 31.8mm clamp.

These parts were on a bike that is about 5 years old, but the cogset, compact crankset, chain, and the jockey wheels in the rear derailleur are only about 2 years old, and probably have less than 2,000km on them. Reason for sale is that they were on my wife's bike, but she's now switching to a 30-speed drivetrain (triple crankset and 10 speeds on the back).

I was going to start advertising them once I make the switch in two weeks, so haven't decided on a firm price yet. However, 300 CHF would seem reasonable. Let me know if you have any questions.