Being a vegan I'd never buy a feather duvet anyway but even if it wasn't morals, an ex of mine once had terrible earache for months, and then one day felt something and proceeded to pull a very slimy, greasy strand of a feather from her ear.
Since then feathers make me shudder. Wouldn't take that if you gave it me for nothing!
But really, realistically, my current duvet was bought for about £20 from eBay when I was skint having had to 'start again' on my own about 6 years ago. I could afford a new one now and could within a couple of years of that period but it does the job so I haven't. Duvets are a much of a muchness for me as I have had much more expensive ones in the past.