IIRC, there was a TWOK Field Jacket project thread over at ASAP some time ago... don't know if there was any progress though. Peter1701 might be able to fill us in... (and please post pics of your jacket.)
Warp-One (or Kronos-One?) over in UK makes a replica. Not very accurate though, and they tend to run small in sizes... had to custom order my XL in order for it to be an XL...
I believe there's a horrible StarFortress version too.
That jacket has been one of my favourite costume pieces ever since I saw TWOK for the first time. It's also one of the toughest jackets to reproduce, and an accurate one might be seriously expensive. I still want one though...