Author here -- I can add DO to the comparison today, I'll ping here once I have done so!

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EDIT: Done!

I have updated the notebook with the digital Ocean offering using their General Purpose (dedicated CPU) droplets.

The major takeaways for DO are that they:

  - Also do not charge for the control plane resources
  - $/vCPU is less expensive than the other providers
  - $/GB memory is more  expensive than the other providers
  - No preemptible or committed use discounts available

For smaller clusters and/or clusters running CPU bound workloads, DO looks like the most affordable option!