Okay, if the airbag fault is so easy to fix why not do it yourself? (thats what i would ask as a potential buyer). To be honest i'd already have walked away as i have previous experience of how expensive airbag faults can be to fix! Plus when the light is on the whole airbag system is disabled so i wouldn't even want to drive the car as it is.
Ex demo car = thrashed from the word go!!
V6 = high tax and fuel consumption
body kit needs painting = £££££
You could get into trouble if you leave the mileage on your add as 12,000.
Dunno what its worth, as it is maybe £1k if you are dead lucky, fully sorted £1500?