duchntr
WKR
Arcteryx atom lt pant might be worth looking at
Here are some options from Wildthings a US company.http://www.wildthingsgear.com/collections/cold-weather-insulation
I picked up a pair of used Patagonia milsurp das pants off ebay a couple of weeks ago. Search under "patagonia mars" or "patagonia pcu" puff pants and they should come up. They're the exact same thing as their das pant only in olive. I paid $75 shipped, although a lot of the new, unused models were a bit more expensive. There were a lot of xl's last time I looked; I got a large to make sure I could throw them on over whatever I was wearing, but probably could have gotten away with a medium. Now my wife wants a pair, but smalls, xs, or even mediums are pretty rare.