You could make a "hub wrench" by putting a slot in a long piece of aircraft plywood or (preferably, but more expensively) a 1/8" or 3/16" sheet of aluminum. You might be able to drive enough upholstery tacks through the spoke holes of the plywood to fix the hub flange rigidly and powerfully enough to use that as a lever. With the aluminum, it would be a mark, drill and tap exercise, with rather small machine screws; but it would be reusable, for when you find another hub from a numbskull seller.