It's more likely that his car is badged 9-3 and someone got the V5 changed so it says 9-3, he most likely doesn't know any different. Anyhow, roofs are generally worth nothing as they are expensive to have fitted and a given the cost of a new roof to what the cars are worth it's not viable even if they did. It's unlikely it will get any bids and ebay will not be interested.