Helium is vastly more expensive than nitrogen, and is in somewhat short supply.
. . . if only we had a strategic federal reserve . . .
I saw a show about the Hemlock Society and suicide kits...a couple of helium bottles from a party store and a plastic bag for a hood. Less than $100 IIRC.
A couple of deep breaths in the hood brings unconsciousness within a minute. Death from asphyxiation within 10 minutes.