I agree sometimes Redbook undervalued some models. Values for FG XR6 Turbos look a little low for example While you are correct it is worth more than a petrol XR6 (non-Turbo), the petrols are not worth much. There is a kinetic blue EcoLPI on CarSales described as excellent condition with 59,000 km for $15,999 which gives you a bit of a guide.