Reddit mentions of Run & Fly Women's Skinny Stretch Mid Rise Split Leg Jeans Indie Retro Rock

As far as not wanting it to be a "mash up" of pieces, good luck. These are custom costumes and not readily available pieces. You'll have to buy separate pieces, do some constructing on your own, and hope they match up and look ok.

you can tell from this image that its a coat and pants.

I think wearing this jacket (remove the pocket buttons for a cleaner look. Hell, remove ALL the buttons and add some Velcro or snaps inside the "fly" to seal up more cleanly) will work best for your purposes. I can't find a stand-collar style jacket or even just zipper-down bomber in two-tone, and I can't find any in white in dyeable materials. Your best bet is probably this jacket.

there are lots of patterns for shoulder pads online that you can follow with foam and cover with a fabric of your choosing so that the size/color matches the costumes (you can see the shoulder pads are a shinier material than the jacket). Attach with craft spikes

For the pants, wear a split-color jean

this mask

these boots

You could always go with this instead and remove the head so as to form a collar (you would then need to buy a different morph hood for the head, in black) and then do the shoulder pad thing. Much easier. You'll likely run into issues with the amount of lycra/spandex in that suit in terms of adding shoulder pads, etc. Its unlikely they'll sit where you want them to. You're much better off using something that won't stretch, like the cotton jacket above.

Unless you're going to a poppy-themed party, no one is going to know what your costume is, so its not like anyone will be scrutinizing the verisimilitude of it. You might have to settle for "the best I can get on short notice".