I'd get a Maine Warden's Parka from L.L. Bean. It has a Gore-Tex shell for waterproofness, Primaloft insulation for good warmth, a full hood and inside storm shirt so you can really seal things up, and a long cut for full protection. Best of all, Bean is selling out their winter stock and you can get it on sale for $200, down from the usual $279. I don't know if you think of that as "relatively inexpensive" or not, but it's mucho coat for the money. Besides, you'll soon be getting annual checks from the Alaska Permanent Fund, so you can afford it.
Other choices? Cabela's makes a piece that's very similar to the Bean offering—Gore-Tex, with Thinsulate insulation—for $210, called (creatively) the Gore-Tex Thinsulate Parka (www.cabelas.com).
Of course, you can also mix and match several pieces. Maybe start with Columbia Sportswear's Thunderscout, a good basic waterproof parka that retails for $80 (www.columbia.com). Under that, layer up with a fleece piece such as Cabela's Polartec 300 Jacket ($50). There, for $130 you've got a pretty warm, dry combo.
Read "Cold Play" from the November '04 issue of Outside for the best in expedition parkas.