A bargain is only a bargain, if it does what you want. The cheap duvets are probably going to be filled with synthetic filling, probably foam. That is fine for heat retention purposes but it will not mould around you as a feather duvet will do. You may also find it is less 'breatheable' and maybe too hot under certain circumstances. We did look at them, and those in Morrison's but what was the point if it does not give you a good night's sleep, and you end up dumping it?. I stillbelieve that you tend to get what you pay for in most circumstances, although if I see a trade name at half price that i want, then I am in there.
We use 2 duvets, a heavy weight feather one for the cold and a synthetic lightweight for the heat. We swop them top and bottom depending on the temperature.
We have just bought a new 10.5 TOG feather one for the van, but we purchased ours at John Lewis in the sales. I fully admit my