I think the situation is that Marstar bought up what, at the time, was the last of the receivers the Chinese had disclosed to them.
Since that time, for whatever reason, China "located" a whackload more receivers and are now selling them to a variety of importers. I do not believe Marstar made statements that they did not believe a couple years ago.
Interestingly, ALL these receivers (even the Polytechs) seem to have been made long ago, in the 1980's or early 1990's. They do not seem to be makign new ones.
I suspect that when Keng's (sp?) was exporting/importing these to the US, they had made a massive run of receivers, believing they would be supplying US enthusiats for years to come. I guess they did not see the 1994 AWB coming, nor Clinton's executive order that halted these importations. Who knows how many are left, but we have benefited greatly from the situation.
If china was still making new ones, they would cost mroe than they do. Even in China, labour rates have gone up and these receivers are actually forged and machine, not cast. This isn't a cheap way to make an M14receiver.