Where do you get a Trench/Long coat that fits, in Brisbane?!

The Steampunk partei is next weekend and I've hit a bit of a snag, my London Fog trench coat is too small [across the sholders of all places!] -it was a tad small when I bought it maybe 14 years ago; but now it is just no good at all.

Apart from the costume angle -I don't really expect to get one before the partei anymore; I'd just really like a nice coat  -y'know? 

So, I'm on the hunt for a Trench or Long coat -Black!- for real person size 4-5XL [thats a 50+ I think?] Wool great coats are not quite right:

1, I don't like wool. -too scratchy.
2, Waaay too hot in Queensland.
3, Always seem to be a little dingy looking.

So, does anyone know where I can get one or If anyone makes them?

Budget is: $200 ...but the cheaper, the better -of course!