Hello,
I'm the seller of these items and yes indeed, I was optimistic, but I've seen 3 recently go for £170, £150 and £120 respectively. They didn't sell even at £80 so maybe the bubble has burst!
The showerproof smock is very interesting as it truly is a one off and I thought I'd put on a sky high price and see what happens. After all, if this is an item you really wanted, you'd be happy to pay. I for instance would pay a small fortune for a new Berghaus Cyclops Roc in size 3 green. Oh how I wish I'd bought one years ago!
I also thought it should go somewhere other than my wardrobe and as an interested collector it's nice to get photos of a rare item out and about. I know from researching the smock myself that very little is known about it.
Anyway, here's a photo I took at the IWM of the only other one I've seen.