Where to get VESA Mount Adapter for 23 inch Cinema Display?

I have a 23" Aluminum HD Cinema Display and I recently purchased a standing desk with adjustable monitor mounts. I have been searching far and wide for the VESA Mount Adapter kit for this particular model of display and have come up short. It seems to be very rare and sellers on Amazon and Ebay are looking for $200-400 (For that price I would rather splurge on a newer cinema/thunderbolt display) for something that should cost about $40-50.

If anyone has any insight as to where I can get this product (M9649G/A), it would be greatly appreciated.