The only realistic way to do it would be to get an importer to bring in the fish you want from a supplier that they use along with one of their normal shipments, pay all expenses up front, and be prepared to lose the lot if there are any problems. Testing for diseases can cost thousands of dollars and an importer is not likely to take the risk. Their normal markup would be at least 100% over all expenses. To try to get one box from an unknown supplier would not normally be on.
It used to be that the importers treated diseases when suspected but now maf have to approve the treatment. Fish are tested for disease and if found a treatment is prescribed, you are billed for the tests and the fish are probably dead by the time a treatment has been decided.