I have one of the 371 Stockmans (Stockmen?), and it's great. My only Buck American 300-Series is a 309, so it is hard to compare because of the size difference, but my Chinese-made 371 has just as good of fit and finish and seems to cut just as well. You can't tell which one is made in China until you see the "China" stamp.
Being made in China often means something is inferior, but with the Buck 300s, I think the Chinese-made ones are fine and are a great deal. You get wood handles instead of plastic, and save a few bucks to boot. You may want to handle a few of them to try and find a good one, though, as I expect the quality control to be lower. So I would suggest going to Wal Mart and trying out some 371s rather than ordering online.
As for 420HC or 440C, I am not sure which is better. But I really like Buck's 420HC, probably because of their heat treat. So I would think the USA 420HC is a better steel than the 440C with the Chinese 300s. But from my cutting experience with both, they are very similar.