It will, indeed, be very expensive. My wife and I completely shelved our plans for a king-size bed (already shaky after difficulties with the bed itself) when the only full-sized doonas(/duvets) we could find were scarily expensive (even mid-range ones were around CHF1000).

I've come to the conclusion that the Swiss don't sleep in beds bigger than a double and larger sizes are only sold here to rip off the rich foreigners.