You certainly don't want to use real Wood's metal as it contains cadmium.
ChipQuick's lead free alloy contains Bismuth, Tin and Indium. They are very unlikely to manufacture it themselves, so its probably a known low melting point solder composition. Indalloy #27 is a likely candidate. *ALL* Indium alloys are $expensive$. If you want to depress the melting point below 125 deg C to avoid chip and board damage there aren't really any affordable low toxicity alternatives.
As pure Bismuth is hard and brittle, you cant simply use that. You could try 58Bi/42Sn solder (138 deg C) but getting small quantities isn't going to be cheap.