Sheets and a duvet for under $200? Not gonna happen. Duvet covers, even cheap ones, cost - there is a lot of work involved in creating them. Sheet sets are the way to go if you want to save money, as most individually packaged pieces are the high-end sheets. I would suggest Overstock, as well, but you're going to find sets there, as well. It's just the way they're sold. Pottery Barn sells nice, not fancy, sheets individually, but they're still likely outside of your price range. You may be able to get a cheaper duvet cover there.