I agree - I feel like I've seen similar jackets in the steampunk selection of Halloween catalogs. I'd check Simplicity, etc in their costume section. They may not have them right now, but in a couple of months...
This link above seems like a step in that direction but it doesn't have the double-breasted front. I checked McCalls and Butterick's online but their selection was a little limited right now.
I have that Simplicity pattern specifically for the coat ;-) although for an interesting jacket tail I also have Butterick 4929 (also single-breasted - I don't think double-breasted looks good on me).
oh these are great resources! Thanks so much!
Perhaps frankenpattern this Mccalls with something with sleeves?
Let me add another:
Vogue pattern #8601 has the same basic princess seams in the body and includes a waistline seam. It is not double breasted however, so you would have to add that onto the front pattern piece: