You know what would be really cool for this kind of stuff ? 3D printers.
Although that belt buckle and all looks plain enough that you could just mod one or possibly even find a "close enough" one. Covering a regular buckle of the right size is probably your best bet if you're picky (I'm going to probably have to do the same thing for the costume I'm making, so I understand).
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