I dropped one from goblin in Rolanberry Field(S) as pld/war, but only one around fifty (ws savage blade points). Maybe better drop with Treasure Hunter.
Its a near certain bet the ALL ingot priced at 5k/60k will sell ALL fairly quickly.
Platinum is used in a multitude of goldsmithing synths ranging from ~55 to 70. (some even higher). Thats an incredibly large gap for single item to be used. A single person can go through 500-1k ingots or more.
That being said, even a 1k loss per item can quickly add up to millions losted for someone skilling up. Which is why 5k/60k will always sell out fast.
Same thing is happening to these as I see happening to a lot of other skillup synths. Certain people make too much at once... then undercut themselves... over and over again
I know most of you are skilling up on these but you have under cut it so much it has turned into a loss synth due to auction house fees. This used to be a 10-15k profit per ingot.