A common ploy by the 'vendor' is to claim they work on an oil rig and can only communicate when they're back on the mainland.
I got this when I went into an advert for a Chevvron microlight at a knockdown price (well I would wouldn't I), low hours, low annual useage, low price. It was advertised on UKGA too and they told me it was a scam and removed it, telling me the scammers usually ask for a deposit which you send then never hear anything more.