one way to get a full aero kit...
https://www.autotrader.co.uk/classified/advert/201906078769114?postcode=wa157ay&radius=1500&advertising-location=at_cars&minimum-badge-engine-size=2.2&make=BMW&body-type=Convertible&price-to=9000&maximum-badge-engine-size=3.0&onesearchad=Used&onesearchad=Nearly%20New&onesearchad=New&year-from=2003&model=Z4&year-to=2008&transmission=Manual&sort=datedesc&exclude-writeoff-categories=on&page=3
https://www.autotrader.co.uk/classified/advert/201906078769114?postcode=wa157ay&radius=1500&advertising-location=at_cars&minimum-badge-engine-size=2.2&make=BMW&body-type=Convertible&price-to=9000&maximum-badge-engine-size=3.0&onesearchad=Used&onesearchad=Nearly%20New&onesearchad=New&year-from=2003&model=Z4&year-to=2008&transmission=Manual&sort=datedesc&exclude-writeoff-categories=on&page=3