Drivetrain

I've saved the best (!) till last. Here's the strategy for the final, albeit most fundamental, section of the puzzle.

Bottom bracket bearings:
 - Shimano MTB (used; XTR?)
 - included with crankset purchase
 - 103.5g

Crankset:
 - XTR M960 175mm (used; triple, for conversion to single)
 - <500g (estimated, after modification)
 - £126.00 (inc.£6.00 delivery)
 - http://www.ebay.co.uk/itm/130768279756

Chainring:
 - Shimano DXR CR80, 46t
 - 139.1g
 - £46.53
 - http://www.chainreactioncycles.com/Models.aspx?ModelID=35272

Chain:
 - Shimano XTR CN-M980 10-speed
 - SRAM PC1091R 10-speed, with Powerlock link

 - 260g (claimed, 116 links)
 - 251.5g (as supplied - 114 links)
 - ~£30 (€35.90)
 - £37.15 (including delivery charge)
 - http://www.bike24.com/1.php?content=8;product=17327
 - http://www.bike24.com/1.php?content=8;product=7391
 - http://www.bike-components.de/products/info/p25061_PC-1091R-10-fach-Kette-.html

Cassette:
 - Shimano Deore XT CS-M771-10, 11-13-15-17-19-21-24-28-32-36
 - Shimano XTR M980 10, 11-13-15-17-19-21-24-28-32-36
 - 350g (claimed)
 - 271.6g
 ~£44 (€52.90)
 - £143.01
 - http://www.bike24.com/1.php?content=8;product=15784
 - http://www.ebay.co.uk/itm/251154658936

Cassette spacer:
 - Shimano CS-HG 1mm cassette spacer
 - 1.8g
 - £0.99
 - http://www.wiggle.co.uk/shimano-cs-hg-1mm-sprocket-spacer/

Derailleur:
 - Shimano XTR RD-M980-GS Shadow medium length 10-speed
 - 174.3g
 - £108.00
 - £107.53
 - http://www.ebay.co.uk/itm/251154295020
 - http://www.ebay.co.uk/itm/251154656620

Shifter:
 - Shimano XTR M980 10 speed trigger shifter, RH rear bar mount
 -  119.5g (including inner shifter cable)
 - £54.99
 - http://www.chainreactioncycles.com/Models.aspx?ModelID=82514

Pedals:
 - Shimano XTR PD-M980
 - 306.8g/pair
 - already got these
 - http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/footwear/Pedals_MTB___BMX/product.-code-PD-M980.-type-..html

I'll finalise things like chainring bolts and outer shifter cable later.