I would say try some boneyards, but I seriously doubt that there are any FiSTs in them, IF there are even any 'salvage yards' at all in your area.
There are some web junk yards online, but they would probably ask as much for a used wheel, as you would pay for a new wheel (sans air bag, and switches, electronics, etc., of course) discounted online, IF Ford even will sell these wheels 'stripped'
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Did you try ebay, or Racing Junk?