AnimaliA, you were not arrogant at all. Very informative nad correct. I have owned and taken care of a few different sharks sp. To say the least owning a shark to thrive is very costly. For bamboo/banded sharks, you can get away with an extra wide tank or square do to it being a bottom dwelling sp. Lepards, bonnets/hammer H., black/white reef tips etc. need round oval or round tanks or ponds unless you can provide 2,000 gal+.
An Ideal tank would be 500+ gal wide tank with a large sump for extra water volume. There are many ways you can filter a tank this size and cheap, except for the protein skimmer. Large and effective skimmer is required. These are messy feeders and produce alot of waste.
The cheapest way to house sharks for optimal captive living is to build an indoor pond, create your own filter, use farmer troughs for sumps " this is were I would place the live rock", correct size UV and oversized skimmer is were the $ comes in.