Riptide, AMM, Sportfish, JBS, Fisher, Rebel, Lightning, are CUSTOM built plate boats here in Brisbane. There may be more, but these are the well known brands. And IMO, true plate boats are not pressed. They are fully welded with a frame, keel, bulkheads, stringers, self draining sealed deck & built to the owners requirements. There is generally a five year hull warranty.
They probably are dearer because of this but that fact will not detract from the qualities of any other boat. If you are happy with YOUR alloy boat then that is all that matters.