I would check direct with the factory. Heard similar stories when I bought my Series 1 4 years ago and some dealers were asking a sizeable premium for a used spare Oz magnesium wheel - one of mine had some corrosion on the rim. I bought 4 new ones from the factory and refurbished the originals in an attempt to future proof this aspect of the car. If my memory serves me correctly, there were well in excess of 100 Series 1 wheels in stock when I got mine as the factory had, apparently, bought up the remaining stock from OZ. No idea what the current stock position is.
I supect the hubs can be replaced in any event and later wheels fitted, but at a cost!
