hi,
in no way an expert, but here goes...
as the saying goes concerning ebay: buy the seller before you buy the item... so hopefully, you'll be fine!
as indicated on this fine forum http://breitlingsource.com/phpBB2/viewtopic.php?f=29&t=42537&p=313472, "Navitimer World - 426A 24mm Navitimer or 443A 24mm Navitimer", so that looks OK... don't ask me what the difference is between 426 & 443! (i have got a 443A on my 2013 navi world).
in my experience, the production week is indicated by w ww/yy and not s ww/yy, although s could be for "semaine" = week in french...
again, the seller seems honest and provides all the right pictures and info, so you should be fine...
happy to stand corrected by the BS gurus!
all the best,
pg