In my experience, this'd cost at least £3-400.
I have a 'tailor' who made me an Aragorn-inspired Outrider's coat, using a brand new custom pattern (because an appropriate one did not exist). The end result was a thick, luxury leather, removable sleeves, extremely well constructed and custom fit to every aspect of my build. Took a while with all the designing, test fitting, revisions etc and finally cost me £220.
This jacket looks like it was based on a motorcycle jacket. I could probably find out the brand(s) too. I also know that at least one of the Rebellion team is a biker.
Tacked on lower skirt (does it continue round the back, or are those just large hip-plates?), cuffs, eppaulettes, collar tabs, stand-up collar, external elbow pads and fine detailing. These are what bump the cost up.
While this exact design has a number of custom details, but even I could do a half-decent job of replicating some of those. So... I reckon find the closest match base model from a bike accessories shop (there are many) and have it altered with the custom bits. Might as well get a pair of trousers and gloves too, while you're there.
About £375 for a basic replica. A fair bit more if you want a great job.
Expect a fortune if you want 100% accuracy, unless your 'tailor' is a leatherworker first and doesn't care what you want it for.
Once people find out you want a copy of something famous, the price tends to mysteriously increase...