a friend of mine used to work for tropical marine (largest uk importer of marine fish) and he had various marine tank set ups at home.
one was a full coral reef setup which looked awesome even had clown fish with anemone like nemo that cost over £2000 and he was in the trade.

later he changed tank and added a lion fish which looked amazing and later still he had a octopuss as well, from what i hear him say it cost lots of money and time to keep them correctly and he always said normal tropical tank can look just as good for way less effort/cash