Well...talking from first hand experience GT parts are pretty scarse!
Got myself a CAT-D GT V6 7 weeks ago and been looking for a second hard OS door, front wing & suspension etc. I've tried everywhere (every breaker you can think of and been checking every day for s.h parts). I did manage to pick up an OS door for £100 from Mitchells Vehicle Dismantlers but had to go straight to Alfa for a wing (£190...which was cheaper than driving to Autolusso at £170 taking petrol into account). If you reply I might be able to point you in the right direction if you provide your parts list.