Ann: Hydrocarbon Samples from Mukuyu-2 Discovery at Laboratory, page-420

I haven't done the conversion of USD to aud then divided by SOI. (currently doing my nightly walk and typing). So will assume you got it right. Its substantial. Helium extraction plant can be small and cheap but its all about scale. I believe the large one we had in Darwin cost 50 million back in 2010 (certainly worth investing when you have billions $ in resources). It recently stopped as they ran out of has to process. For those interested in the process.. .

How Is Helium Extracted?
Helium is mined along with natural gas, using a drill rig to drill wells deep into the earth’s crust. A drill rig must penetrate a layer called the Cap Rock to reach a natural gas reserve. Once located, the natural gas and Helium rise and fill the rig, which are then led through a series of piping systems that transport the natural gas and crude Helium to a refining plant.

Most crude Helium tapped from natural gas reserves is only around 50% pure, so other gases must be separated through a scrubbing process. There is a significant amount of Nitrogen in crude Helium, as well as methane gases that must be removed. Cryogenic separation units compress the crude Helium, cooling the gases at subzero temperatures until they are liquified. Once liquified, the Nitrogen and methane gases are drained.

After this cooling process, heat and Oxygen are added to remove any Hydrogen left over. When Hydrogen and Oxygen molecules meet, they create water. The gases undertake an additional cooling process, in which the Hydrogen and Oxygen are drained from the mixture. Once Helium has gone through each of these steps, tiny particles are added to complete additional purification until the Helium reaches 99.99% purity.