I had to order one from America - I think it was about £21 with P&P and taxes etc. but it does stop the rattle which suggests some movement so worth the investment.
If you cant find one let me know, I would be happy to send one to you, you cover the postage, no extra fees! I ship worldwide every day. USPS airmail should be about $10 shipped in a bubble envelope, the product is listed at $20
Please note, the Slop Stop that I am aware of is for the rail on the MFT/3. It does not attach to the saw itself: