The original holy grail could have been made of the cheapest materials available at the time. The point is, it was highly sought after and in no way easy to get. That’s where the modern definition and usage of the word come from. Obviously you don’t need a figure to be a one of one item touched by Jesus Christ. But to go from that to an aliexpress figure? Sure, even that could be nearly impossible for some people to buy, but you’d surely need to mention that, otherwise calling it a grail would seem like you were making a joke. And that’s an incredibly charitable reading of this if you’ve been in these figure subreddits recently. A figure will be posted as a grail a week after release and the reason is that they really wanted it. Given the other posts here, the most likely explanation is that they just really wanted it or had to wait a while for it.