well, the salesman will tell you very cheap to maintain.
that is only getting tank, salt and deco and a few cheap damsels Total initial should be within $300. later, you have to get water treatment machines like skimmer, denitrator, calcium reactor with CO2 injection on solenoid module, chiller, surface skimmer and a host of additives plus test kits, you can look at spending easily $8k or more for a 4feet tank. Plus, you will see a $200 rise in your electric bill with your chiller running 24/7... i know cos i kept a small shark before at home for several years:sweat: i became a slave of the hobby though i enjoy hand feeding the pet everyday.