Given the impact the model might have on the world, and that $600k is roughly equal to the annual salary of 1~3 top notch engineers... it's probably intended to mean relatively cheap.
For similar context, millions of VC money have been thrown around for much less impressive results.
Spot instance pricing for p4d.large is about a third the on-demand cost, though it's not clear what they're using to calculate market rate. An A100 card is roughly $10k retail, so it's not like "owning a GPU cloud" is that cheap a proposition either.
I have no context for this, do other model dveelopers publish how much it costed to train them?