NA Miata rekey

Has anyone rekeyed their miata before? I have a 96 NA that only came with one key from the person I bought it from and I lost it. I went to the dealership to get a new one cut from the VIN but it did not work, so it likely has been rekeyed in the past or the ignition cylinder had been swapped out previously. Does anyone know how much it costs to get this fixed?