Have you considered doing a vinyl wrap yourself?
Do some google searches on BMW Z4 interior vinyl wrap - scroll down to the bimmerforum article - best of all easily reversible if you are unhappy with the results and pretty cheap to do.
I have some brushed aluminium wrap on order for my interior and will update on the forum with my results.
Silver grey Z4MC
Mods: Strongstrut 3 piece / CDV delete / Stormwerks ST1 gearknob / clutch stop / stubby / ipod integration / LED interior
Work in progress: Exhaust tweaks