I've been saying that for quite some time. Unfortunately, nobody wants to hear it.
CCR people are very happy to talk about using helium whenever they feel like it.
A deepish and longish dive would use as much as 60 litres of helium -- call it 10p/12c, then it's a mere £6/$7.20 per dive.
Plus another 120 litres of oxygen -- about 1p/1c = £1.20/$1.50.
Plus the sodalime, about £5/$6.
Plus a pee-valve catheter, about £2/$2.
And the boat fee, £60/$70.
And the diesel to drive to the boat.
And lunch. And a nice day out.
All for £100/$120.
Alas the cost of a twinset fill for a 60m/200ft dive would be ££££++ / $$$$+++. Plus all the oxygen for the deco gasses.
The best bit is this: I'm gassing up for a 65m/220ft dive on Friday. The weather's a bit marginal (after a long spell of hot weather, sorry everyone, it's my fault for booking a dive...). The alternative dive site's about 50m/165ft. I won't be changing the diluent for that. Nor would I bother changing it if we went to a 30m/100ft site. For a few quid, it just doesn't matter.