@Papahuge them's the rules, sorry, and not made by me. But I agree with them since we've seen stupid games with sellers happen on here before and it's infuriating. Which is why the rules are there.
It might help to sell your stuff more quickly if you put prices on main units and assemblies, and/or a price on the lot. e.g. for the doors you want X, for the seats and trim you want Y, for the engine you want Z, for the whatever transmission you want A, for panels C, for lights D, and the whole lot for E.
