Well, I've been Surfing t'Net and I've bought something already
Most of these sort of things are fairly substantial hut slippers or mules, or very expensive top class makes for serious mountaineering
I wanted something softer and lighter that I could carry when I'm backpacking, and more reasonably priced if possible
I would wear them mostly for lazing around in a backpacking tent or as bedsocks inside my sleeping bag, and only occasionally outside
I found Nordisk Mos Down Shoes. I don't think they're the best, being, I think, sewn through, but they should be good enough for what I want. They weigh about 180g.
It looks like they're being discontinued, and are being sold off by various suppliers for about £20
I take size 11/46, and those are almost completely sold out, but I found a pair at
www.absolute-snow.co.uk ; green only. So I bought them while they are still available
But there is a better choice in the smaller sizes from several suppliers; just Search Google