Going on a tangent here, not a He diver myself, but I was actually talking about this with my uncle, who worked in cryogenics in France. Dealed with all the big unis, CERN, the military, you name it. Met Charpak. Getting helium to fill balloons never was a problem

Anyway.
- Helium pricing is very much what they care to charge for it (esp here with apparently only one supplier). Maybe you could save by pooling.
- Uni dive clubs, if they can, use the boil off from the cryo labs. Cryo labs have the kit to recompress it, med ones (they also use helium) don't. Any of these in Ireland?
And, irrelevant to the discussion at hand...
- Spectrography is the only way to reliably measure helium content.
- DIY filters. Use coconut charcoal.
Cheers,
Matthieu