[Dan, carefully considering something that doesn't really deserve it...]
Hmm.
Not a bad finish for corrosion resistance, but a real expense when it comes time to replace the consumables -- chain, chainring, cassette, brake discs.
Practicality aside, I'll bet most of the materials costs were in the headbadge diamonds. Gold being gold, only a little bit would go a long, long way if it is electroplate.
Best,
Dan. (...who figures at the equivalent of £607,686, that bike's cost would equal almost 268 base-spec Nomads or 450.5 base-spec Audaxes)