I just remembered - a similarly weaved toli-toli gold necklace from India about 3/4 the length of the toli-toli on the Riau-Lingga keris, with a modestly gemmed broach at the front was on sale in an antique shop in Singapore. I reckon the weaving was the exact same technique employed on the Riau-Lingga keris. Cost of the necklace - SGD15k.
If we were to consider the cost of the more elaborately gemmed broach, the top loop, gold sheath, pendoko, and hilt, and add on the provenance value, I think we have a stratospheric value for the Riau-Lingga keris.