Forum member power90801 (Rob L.) kindly sent me a link to this NOS 7A38-7180 SAA055J, posted FS on Instagram a couple of days ago by UK dealer orangeclockwork007 with a fairly hefty asking price of £550 (not including shipping).
He's only bothered uploading the one photo. Unusually it hasn't been cropped to Instagram's default square format.
I hadn't spotted it myself, because the seller hadn't included any of the hashtags like #seiko7a38 or #7a38 I regularly search on (nor anything else remotely useful). Checking his feed, he'd posted this typical 30-second hand-held video (with birdsong as a sound track) the previous day, which shows the case-back's pristine JWCII inspection sticker.