Most of the repros are out of Romania and yes, it does seem that Chinese outlets market them.
There were, in the past, (and I mentioned this in the GMB some years ago) repros of these types of items from at least one maker in the USA. He sold via eBay with his listings stated as "Reproduction" but without his own mark of any kind on the work. Hence, in the secondary market, his work is hard to separate from the Romanian (etc.). He claimed to be able to produce reproductions of all the main cameo makers and was even, in his own message board, talking about making repros of Thomas Webb cameo!!! He disappeared from eBay some time ago but I have no idea whether he is still producing such items.