If you're buying liquid fixer and having it shipped you are paying a large shipping charge for a lot of plain water and some chemicals. I think you would be better off paying shipping on just the chemistry.
Buy a jug of distilled water - not the 'pure' bottled mountain water people drink - Steam Distilled. You can find it in most markets.
The triosulpfate/bisulpfite ratios mentioned above will do it. I've become accustomed to heating 750mL water to 52c and adding the triosulphate and when disolved add the bisulphite and stir till disolved then top off with water to 1000mL. This is wortking strength, not stock solution. Use if for film and paper as is - but cool to your working temp.