Those emergency blankets, if they are the ones I gave out to people at the Brazda Refugee Camp in Macedonia in 1999, are warm but not very robust. They seem to be made from reclaimed wool that is chopped and rewoven into blankets so they are multicoloured and what not. This isn't a problem in itself, but they aren't as robust as a proper woollen blanket.
There are links to British Army blankets on the forums, they can be a bit itchy at first but if you wash them with some fabric conditioner a few times on a cool wash and air dry them out on the line they soon soften up.
The US army blankets are a nice green colour! Trying to get them cheap though is a hard deal. There are green blankets used by British Army Medics, but I have never seen them up for sale yet.
Basically, if it is 100% woollen, you can't go wrong, if you want an inner blanket that is soft to stop the itchiness of the issue blankets, use one of those picnic tartan blankets that you get in the petrol station, they are surprisingly warm for such a thin blanket, soft and light.