I bought one from Kitbag.com.au, based in West Australia. It's a military style bag, mummy shape, but it's the biggest sleeping bag I've had. Too big for me really, but I like it just the same. Fits my son, who is quite a big chap now that he's grown...he usually feels very constricted in a sleeping bag. It's flat filled, so there are no cold patches where quilting is stitched, and synthetic, so if it gets wet, it'll still keep you warm. It has a reinforced section at the bottom so you can sleep with your boots on, neat idea, but probably only necessary if you expect to find yourself under enemy fire during the night, and need to be ready to flee at a moment's notice.
I bought a polar fleece liner online from an English site, it's warm enough on its own in warm weather, and packs down very small, although its own bag is not particularly tiny. I just sqeeze it down into a small dry bag. For very cold weather, as a liner inside the sleeping bag, it's blissfully toasty. I've bought a few camping items from the UK, because they make things warmer over there, where even summer nights are nippy.
I always use a sleeping mat, it makes a big difference, as it prevents heat loss to the ground underneath. I got a fold-up one, I like the folded shape better for packing than a roll, but that's a personal choice.