yea fish here are dirty cheap. and if one buys in china, get the feeling you are in a liquidation sale. 3 foot aligator/cuban gars for 20 bucks. non monster (common) fish are even cheaper.
But local enthusiasts are not that big on monster fish. Chain goes something like this - japanese get into it, then the taiwanese follow, and trickles down to chinese ... what they can breed in china, poach out of indonesia and surrounding SE asia can be aquired cheaper relative to rest of world.
fish from amazon or latin americas are harder to source here in asia and at a huge premium or very very patchy supply. from what i see online, the fish are sold cheaper, just the shipping costs may negate any savings.