I would probably start by freeze-framing and getting some better reference pictures and from all angles. This will really help you or whoever makes it.
It depends on how picky you are. A tailored suit is a very advanced project and you're not going to find something just like that to buy. You could try searching "Mod Suit/Jacket" with things like "purple velvet" but it depends on how picky you are - you might be able to alter something, but it won't be quite right - and you'll probably pay quite a bit for the not-quite-right jacket.
With something like this, you would have to make the pattern yourself. You might also be able to pay someone to make the pattern for you. You could try to go to a fabric store and look at their pattern books and they might have something you would find acceptable in the costume section - but they won't really have a great tailoring pattern.
If you have any idea of what route you want to go - make or commission or whatnot - then it will be easier to give advice.
It will also help to know how much you care about accuracy and whatnot. Going to look at costume patterns might work out fine for you and might be your best option if you're not wanting to get super crazy about this. If you do want to get really into it, I can try to direct you to basics on how to draft patterns - but I'm just warning you that something like this is very advanced so if you've never done pattern drafting before it might make you very frustrated to try to do this your first time.
Disclaimer : This post written by a Grumpy Old Man
Actually in the pipes:
- Remaking Ser Loras doublet.
- Luke Skywalker, A New Hope
- Wind Waker starter costume in swim material
Eventually: Paul from Dune, Faramir, Harry Sullivan