Ti-goat
Seek outside
Four Dogs
Helsport
Kni-co
Tentipi
These things dont come easy, unless you're willing to buy new from abroad.
Or you could always drive over to tamarack...
http://www.tamarackoutdoors.co.uk/PBSCProduct.asp?ItmID=9152412 Go see Mike and the gang. As you know Dewi, they're a top bunch.
One stove not mentioned above is the Liteoutdoors Ti cylinder stoves. Their newest offerings include a full-size door with the vent low down for better burn, and they have replaced the top cables with solid bars for better cooking options. Not tried one personally yet, but give comments on those I have used in sub-Arctic and Arctic. An important rider here is the size of the tent you're heating! Also need to bear in mind that lightweight stoves tend to put out all their heat quickly - which is fine for warming up the place fast, but less good for keeping the tent warm on an ongoing basis. 1-1.5 hours is the most you can expect from a lightweight Ti or SS stove (possible exception is the Fourdog titanium stove, but check out the cost!). Cast iron, and efficient damping, gives a longer effective burn, if slightly slower to bring to temp.
1. Seekoutside - Large Ti stove. Good design, easy to put together, good low vents on the front. With decent wood it would work fine in a 6-man tipi or smaller down to -20C. With damp wood, as a group of us found in the forest north of Oslo a couple of years ago, it used virtually all its heat just to part-dry out the wood-pile!
2. Shepherd stove (Hillpeoplegear). I used this in Jokkmokk last November, with temps down to -27C in an 8-man Seekoutside tipi. Burned well, was nice and warm, but needed refilling frequently - no "throw in some logs and it'll burn all night long"
3. Kifaru - they only seem to be using SS ones now from their website - no Ti. In my opinion, a slightly inferior version to the SO range, mainly because of their vents which are too high up the front - again all this is my opinion. To be fair, in a 4-man Kifaru the medium stove could create a sauna in temps of around 0C - literally too hot to go into the tent when the stove was roaring with a full load of wood.
If I were getting a new stove for my 8-man tipi for winter Arctic conditions, I'd first of all get a liner for the tent to cut down heat loss through the fabric. Then, if I had over $1000 lying around, I'd probably get the Fourdog large Ti stove. Back in the real world, I'd get the Seekoutside XXL SS stove for round $450.