While I can believe Russian health and safety standards aren't the best, I doubt very, very much that the $4–5,400 price difference per shell is spent (entirely) on improved working conditions at western factories. That's potentially the most outrageous thing I've ever heard and I once spoke to a jellyfish, which did not respond. But if I were to speak to it again, it might say something like this:

The answer is right there in the prose. The price difference is because the Russians save three millimetres worth of metal for every shell (it's probably 3mm³ but the text isn't clear). That metal could even be wrought iron, which doesn't come cheap.

The west should make their ammunitions smaller than the Russians'. Maybe start with just a small decrease in size, like 149mm. This would, by my calculations at the correct ratio and taking health and safety into account, reduce the cost of each shell to roughly $5–600.

The Russians aren't silly and they do like an arms race with the west. By Christmas they are likely to go even smaller. Maybe down to 146mm @ $60. Now we see there's a predictable trend and what the Russians won't know is that the west has already started to produce 143mm shells at the same price!

Eventually, the west will be able to fit two shells into one artillery-thing, which is bound to have some advantages. For a start it will solve the problem of not having enough weapons because every weapon will now be twice as effective.

Eventually, if the west keeps going with this winning strategy, the cost of it's shells will become $0. Some time after that, the size will become 0mm, too. Like a good game of Connect Jelly 4, if the west drops it's pieces right, the Russians will get to zero first and then won't be able to fight at all.

Personally, I would not take advice from a jellyfish even if it was sentient. It would probably just spook me, tbh, and they have the right shape to dress up as a ghost, too.