FISH. Where is the best value? (Hong Kong)

Hi all
As my parents are coming to town for the first time, I'm planning to take them on a culinary treat.
I've already planned for the fancy Hutong, the Peninsula tea, etc.

Now what i'm looking for is the best place to get good fresh fish and seafood, like the ones where you select your fish in the aquarium (thats quite easy so far, you would say) but Ive added a condition: GOOD VALUE as well.

So, what do you suggest?