If you are only looking at a very cold weather parka, and intend on sitting for a long time, go with a straight down parka. Don't worry about liners, since you should be layering anyways, and will have clothing between you and the parka, and don't worry about waterproof gizmos and other things, since the only water you are likely to see at -30C is stuff you brought with you, or stuff you are leaving behind.
I'd vote for something along the lines of North Face's Nutpse (sp?) jackets. They have several 700+ fill power down jackets that should fit your bill nicely. STP, mentioned above, has these jackets at a nice markdown right now, and has a few other down jackets to choose from as well.
Cold Weather Warning!!! If you intend on doing anything other than sitting down (ie, jumping out of the tree to go chase down the walking freezer-meat you just shot at) you need to be very careful about heat management. Down is a great insulator, but _will not_ keep you warm if you go running through the woods with your adrenaline pumping in the same layers you sat around in all day, and sweat your eyeballs out. Be conscious of how warm you are, and act _before_ you begin to sweat. Afterwards will be too late.
Now that we've covered that, my personal choise would be a heavyweight mackinaw from Filson, provided I could afford it (I can't afford the Nuptse jackets either). Filson makes fantastic wool clothing, and my choice of wear (Which would probably do me for most activity down to -30C) would be heavyweight poly-pro, nice and thick wool pants and shirt (I have some belgian mil pants, and woolrich shirts) and a good, double-thick mackinaw. Wool will be quieter than the nylon of the down parka as well, and be better if conditions change, or you do a bad job of heat management.
Stryver
