Black caps are quite shy at first, but they will get to know you and come out a lot more. They take anything you'll feed them, they're REALLY fond of mysis and blackworms.
As for the price, they're not cheap anywhere you get them from because they're a deeper water fish found below the 20m mark. They fetch $120-$150 here in the US. The reason they're so much more there is the same reason that Aussie fish are more here, shipping.