TF-3 stock solution - 800mL of 57-60% Ammonium Thiosulfite per litre, then 60g sodium sulfite per litre, then 5g sodium metaborate per litre.
Use at 1:4 for film or paper. pH can be fine tuned to be closer to TF-4, so it smells of ammonia less.
My closest supplier that I chose to look for of Amm Thio was Claire at JD Photochem, who has stopped trading. The seal on my last gallon jug from her has recently been cracked.
For the fixing after that I will be going with Ilford Hypam. I picked up 5L of Hypam stock at Film Plus for less than just the 60% Amm Thio per galloon cost me from Claire excluding her shipping costs.