I know this NPC exists in both capitals, Idont know where in Thayd but its close to the Elder Gem guy.
In ilium, the NPC is called "Arvir" and is a <Augmentation Vendor> who sells Pulsar Neuro Implant for ~60s, it's a lev 15 implant that can be savlaged for Intricated Rune fragments & rune fragments, with a pretty high chance.
Location in Ilium: https://i.imgur.com/v0lfzA8.jpg
If you want to abuse this, do it NOW while the rune prices are still high, just go to the AH and sell them instantly as you'll make insane profit but this will only work while the rune prices are kinda high and I'm sure they'll plummet in price when this goes viral.
I've already made over 50p with this method.
Goodluck guys!
TL;DR
Buy Implant for 60s
Salvage
Get shitton of rune fragments & intricate rune fragments
Profit