I've only had my TF for 18 months but this is the 3rd or 4th time I've seen a request for one of these, it appears they are NLA, your best bet is to look for a complete rough/damaged rack and then make a profit selling the other 3 feet.
I was looking last year for a rack and although it took time searching I got a good one off FB marketplace bundled with other parts for £60 + £15 carriage. I thought that was a bargain until I sold one of the other parts (VGC tonneau) for £130 on ebay, the bargain suddenly became a profit.