Great news Lurch.
Firstly the colour looks like Gun Metal to me.
Cheap mods for around £30 odd then you are looking at things like;
A stubby aerial, chrome wheel valve dust caps, gear knob, LED bulbs (sidelights/number plate lights/boot light all 501 bulb ~ interior 32mm festoon), Assad air vent covers, new oil cap, new rad cap (1.3 bar uprated version), performance panel air filter, Flyboy 2006 airbox conversion kit (£35 odd), Marks chrome bonnet latch (£35) etc etc
Some links:
http://www.350z-uk.com/topic/69409-genuine-rdx-stubby-aerials-decal-15-delivered-special-offer/
http://www.350z-uk.com/topic/86033-bling-that-bonnet-catch/
http://www.350z-uk.com/topic/86240-new-batch-2006-airbox-conversion-kit-interest-list/
http://www.ebay.co.uk/itm/4x-ERROR-FREE-CANBUS-8-SMD-LED-XENON-HID-WHITE-W5W-T10-501-SIDE-LIGHT-BULBS-/290617035424?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item43aa200aa0
Plenty of traders on here to help you spend money on your car and always worth checking out the second hand section for bargains.