It looks to me that you’re asking about
swivel seats in general, so I’ve taken the liberty of editing the title, as there aren’t that many aftermarket seat options for Transporters (unless you include seats from other vehicles, which isn’t really aftermarket, more a modification) nor aftermarket seat-base options - the seat safe or shortened height base being the two I’ve heard of.
OEM Seats and OEM seat bases bolt together like tyres and rims: provided they’re meant to go together, they will. Since the T5, I think all seat trims and bases match size-wise (T5, T5.1, T6, T6.1 for your forum / eBay searches)
There are aftermarket swivels out there - plenty of info exists here. Try searching ‘
swivel seat’.
I imagine the seller is referring to the pricing - captains drivers seats are ten a penny - after all, all vans have a single seat, the captains element is usually referring it to having a swivel base, whether that be OEM or an aftermarket one. Captains passenger seats on the other hand are expensive as most vans came with a double-seat, which as you’ve found can be uncomfortable and not suited to a camper.
Can you confirm if it’s aftermarket seats you have, or if it’s just aftermarket seat skins the converter has fitted - photos of the trim and the seat sat on the base will help.
Again, it depends what you’ve sent to him as to whether hes talking about swivels, bases, or non-VAG seats altogether. Plus, when it comes to buying, who can you rely on to be genuine?!
You have a T6.1. It’s a face lifted T6, but with the differing trims and parts internally, it’s best to keep to calling it what it is.