In 1975 while on a 30 day Greyhound bus pass trip from So Cal to the Canadian Rockies, at the one and only REI in Seattle WA I bought an expedition down jacket for $75 (5″ loft, the common way in those days to measure how warm stuff would be).  Also a pair of expedition down pants for $25 (3″ loft).  The pants had zips on both sides of the legs and could be zipped together to make a 2/3 sleeping bag, the opening at the bottom had a drawstring to close it down. I used this as a sleep system and it worked pretty good.
I also had an expedition sleeping bag with 9″ of loft, a lighter weight down jacket, and a down vest. Â I stayed up in the Canadian rockies until December, lurking around Banff and Jasper. Many nights it was so cold I was in that sleeping bag with all my down on! Â I finally left after a -40f snap and went to work as an unpaid slave at my dad’s nightclub in New Orleans – one month of that and joining the Army looked attractive, so I enlisted.