Nope, Haven't seen that style of shirt before, but it does look good! Might have to put one on my Christmas list!
Found the blurb for it on another retailer's website where they're asking £85.00 +P&P for them:
Same material as Ranger Shirt, loosely woven (light weight) 100% pure New Zealand wool and with the same waterproof properties as the Ranger - really will keep out the light rain and drizzle. This garment is possibly more flexible than the Ranger shirt being 'Shirt' style with full length snap-popper closures at front for ventilation, plus button cuffs. Two button down breast pockets.
As for the eBay seller, I've bought a Swanni Mosgiel and a Swanni Ranger shirt from him in the past and was very happy with the service I recieved. I'd ordered an XL ranger and found it to be too big and he exchanged it for a Large with no quibbles at all. Spoke to him on the 'phone and he seemed like a nice bloke.
No connection with the eBay seller beyond being a satified customer!