I need a reusable 1920's/Peaky Blinder costume. Help!

[duckme]

I have a fancy dress party to go to and the theme is Peaky Blinders (which I've never seen) or 1920's. While I don't mind fancy dress, I really want to try to avoid the throwaway, Amazon type of costume. It's a waste of money and is wasteful in general. However, I'm struggling to find a suitable alternative. I want something I'd wear again so I'm thinking a flapper dress may be out, but if there is a subtle one anyway, it could work. I did think about doing a women's version on the three piece suit the men of Peaky Blinders wore but I don't know where to start looking. I'd be grateful of any advice or links. Im not a small girl either, a curvy 14 and my arms are flabby and don't need to be on display!

Ebay is your friend!

For a Peaky Blinders themed birthday party a couple of years ago, I looked at ‘costumes’ and decided the key was in the detail, rather than the actual clothes.
I wore a black sleeveless cross-over dress with a ruffle down the front that I already had, knee length; black round-toed heels with an ankle strap (again already had), a faux fur wrap (£5 from Primark), and cheap art-deco style earrings/necklace. Sparkly clutch bag and done.
Oh, and I’m a bigger girl, I felt MUCH more comfortable in ‘proper’ clothes rather than a costume.