cranks: you can use tiagra, which will shift just as good. Not as pretty, but gets the job done.
BB: ultegra, 105 or tiagra, whichever you can find cheap. Ultegra is often the cheapest for some reason.
chain: just buy whatever you can find for cheap. sram seems to wear out faster than KMC and wipperman.
tubes: whatever will fit.

saddle: personal choice, but many would recommend brooks B-17
handlebars: personal choice.