They don’t sell it anywher
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They don’t sell it anywhere in North America. Sony discontinued the product some time back. B & H Photo lists the item as discontinued and unavailable. eBay has no current auctions or stores listing the item. So good luck finding one. The forums are littered with requests for help in finding the adapter, all ending nowhere.
So for the mechanically inclined out there, it shouldn’t be too hard to locate the proper connections & build a mic adapter. And from what I’ve seen, you could make several hundred dollars selling them to folks like both posters here.