Ophuira is right, you need to look into the less active, bottom dwelling sharks. I have an epaullette and am working on an upgrade to a 240 gallon tank. He is a good shark for the home aquarium because they do not get excessively large nor do they swim freely, (they "crawl" on their fins). Additionally, these sharks will breed relatively freely in an aquarium. For a 240 gallon, expect the following costs:
glass tank w/ tops: $900
stand: $700 (save $ if you can build it yourself)
wet/dry filter & protein skimmer: $600
heater, sand, live rock, misc: $350
These are just estimates but are pretty close. If you can afford to do this type of tank, it is very rewarding. Bamboo and catsharks are beautiful to watch and can be very hardy if kept appropriately. Do not attempt a free swimmer (leopard shark, blacktip, smoothound) for a tank of this size because they will continuously bump into the glass and will inevitably get injuries/infections.