Thanks for the replies.
Portland Bolt did not seem interested when I contacted them a few weeks ago. They wouldn't even provide a quote.
I have reached out to the other suggestions posted.
It seems like if you want non-China, then they are only available in plain finish. Luckily, there is a metal finishing shop about 6 miles away that can finish plate hardware. I was just hoping to that we would have to add the extra step of plating the nuts ourselves.