You might be able to buy the really old fashioned quilted type eiderdowns in large charity shops but I think they've been largely replaced by duvets these days. If you particularly want a feather based one rather than a polyester based one, look for duck down or goose down, which are usually much more expensive. We've had both over the years but I find the modern polyester ones much easier to wash, either in the bath and drip drying spread flat over the Hills Hoist, or putting them in a large washing machine.