Its probably not want you want to hear mate but I have a personal limit whereby I wont buy anything on Ebay over £500. I sold several items on there in the past and it is so painful as a seller I cant see how any serious small volume watch seller would chose to use that medium. Its a different outlook if they are an established trader with a 'storefront' on EBay.
In my constructive opinion any watch over a £1000 would definitely warrant a face to face. This hobby of ours is just too fraught with chancers.