I bought a down comforter 10+ years ago with the year's tax return. It's still going strong. Maybe it's a little less warm than it once was, but considering I spend 20-25% of my life in bed, it was worth it. I'd guess it's saved me money too. I haven't used central heating most of my adult life.
Down is the best. One of my oldest possessions (maybe my oldest, actually) is an old down sleeping bag. It's warmed me on many a night.
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