[eesmith]

You likely meant to write 'xenon' there, not 'helium'. FWIW, https://en.wikipedia.org/wiki/Xenon has

> Because of its scarcity, xenon is much more expensive than the lighter noble gases—approximate prices for the purchase of small quantities in Europe in 1999 were 10 €/L (=~€1.7/g) for xenon, 1 €/L (=~€0.27/g) for krypton, and 0.20 €/L (=~€0.22/g) for neon,