In the part of the country I'm from (Western Australia) it is even harder to get exotic fish.
I feel you mate, I'm in Tassie so I know exactly what you mean when you say "strict" import laws. I guess that's the trade we make for living in such a beautiful and unique country.
As for prices I've never seen any "monster" fish for sale down here a side from two big peacock bass (and I can't remember how much they were, nor do I know what kind of pbass they were) so I can't give an estimation on what monsters would cost down here, but I paid $25-$30ea for my synodontis nigriventris, and apparently they're cheap as chips overseas.
$30 for my short finned betta.
$45 for my silver saum @ 2-3"
$30-40 for a 2-3" silver dollar
$65 for an L397 plec @ 1-2" (prob more now if they were to ever come in again)
I can however tell y'all how much tanks down here cost... My ex and I spent a little over $1500 on a 400ltr (approx 100gal) tank, stand and hood. Unbranded, no warranty, no accessories. Just a glass box, wooden stand and cheap metal hood that doesn't even sit on the tank properly... That's what $1500 will get you down here.. Not freakin' much!