In the last few weeks I've replaced quite a few parts in my current Z4 and I still have a couple of little bits from my previous Z4s. Happy to arrange shipping if needed.
Individual Champagne Mats - sold.
Beige Mats - £30 posted.
Z4M Illuminated Gear Knob - £45 posted. Illumination works and it's in fair condition, price may seem steep, but get a quote for a new one... E86 Z4M OE Springs - got history showing they were replaced by BMW in 2018ish. £50 collected. Could arrange to get the rears fitted for the buyer.
Z4M Spark plugs - £20 posted (in NGK boxes from the set I've just installed). 3k miles on them with history to prove (ordered spark plug for Insp II before realising they had been replaced in the last service the car had).
Z4M Air filter with 3k miles - Free collected.