There is no way on Gods little earth that a private metal detector outlet/buisness in Australia can sell detectors made in the States at the same price as the yank prices.
There is not much profit in detector sales alone and you need to retail other stuff in order to turn enough profit to pay for the running of the buisness and put food on the table.
If you are running the buisness as something to do in your retirement and are working from the house or a shed in the back yard (to eliminate rent)well good luck if you can keep it going.
First you have to get a loan from the bank to set the buisness up and to buy stock, and advertising so there goes at least 100 grand and you have to pay GSt on every order that is over 1000 dollars plus shipping costs and certain Customs charges.
In order to turn a usable profit in any retail buisness you will have to sell your product at a round 3 times what it cost the buisness to put it into stock.
So any Tesoro for eg that costs say 600 bucks RRTL in the states is going to set you back at the very least 850 bucks Aust and even then the dealer will have made buggerall profit which puts him between a rock and a hard place because he cannot ever match the American price and expect to stay in business.
Just an opinion.