We just covered this, and with some assistance in covering the outfield, Sierra Trading Post, Army/Navy Surplus and Uniqlo won out.  Need Supply Co. is carrying a pretty decent-looking number from Spiewalk, but I cannot speak to its quality.  And if you are feeling adventurous, check out this interesting camel peacoat by Fidelity for Barneys.

Depending on your definition of “affordable,” however, you may want to take a look at this bad boy from Rag & Bone—I’m due for a peacoat myself, and the navy with beige detailing version has been the frontrunner for about a two weeks now (though I can’t seem to find a picture of it on the Internet).