RE: Endangered elements: Let's save helium.
I read a bit more on it.
This reserve storage was leaking, and it was costly to maintain, particularly the latter point drove the decision to sell off the helium.
If I understand it right, it's not that super-trivial to just take the helium out of the storage - it has to be tapped at constant rate, so it's totally unsuitable as a buffer. It's also nearly empty, with the tapping rate being much lower than when they started selling off helium.
Helium is notoriously difficult to store, this causes a quite inelastic market situation and can explain that there are temporary outages in the same time as there generally is a glut in the market. However, googling for helium price charts, I didn't find much volatility. Prices have steadily been rising over the years.
Yes, in fact, one of the main storage methods is to combine it in tanks with 20% oxygen. But it has great limitations.
You can check this article.
http://assisted-dying.org/blog/2015/04/24/australian-warning-on-diluted-helium-tanks/
As I understand the quoted article, they've started selling party balloon helium in the Australia with 20% added oxygen in order to prevent deaths from people inhaling the helium (either as a party trick getting squeeky voices, or as a means of suicide). The article recommends anyone planning to suicide by helium inhalation to check that their helium doesn't contain significant amounts of oxygen.