Some of the cost isn't just from using the equipment, but because you'll have some evaporation from melting in vacuum. He says at the start of the article that Sacks started with a kilogram of beads:
>After melting from both sides and a lengthy cool down period (plus a couple of "ouch, where are my gloves" moments) Sacks' iridium was consolidated into a block a little over 2" square and less than 1/2" thick, weighing 1.7 pounds. It's startlingly heavy, distinctly more so than a similar sized tungsten block (which would be about 15% lighter and about 10,000% cheaper).
If true, the melt lost 22.7% of the mass, which is pretty painful. Google is saying iridium is about $167,000 per kilo right now! I assume they've got a cold trap on the vacuum line, and recovered some of the difference in weight as fine iridium dust, but the rest is going to end up coating the inside of the vacuum chamber.
If they routinely melt platinum-group metals, I wonder how often they scrap the entire chamber to melt it down and recover the evaporate.