Thanks for making the container runner! I just set it up in EKS. I’m wondering whether artifacts, workspaces, or caches work with the container runner?
They do all work: CircleCI’s self-hosted runner FAQs - CircleCI
That’s great! I’m assuming we pay network transfer to internet costs and CircleCI manages the storage and retention of the caches on your side?
I imagine if we want to avoid network and CircleCI storage costs we could build out our own orb that saves to a S3 bucket with a lifecycle policy 
We do manage the storage and retention on our side. You pay for the network transfer from CircleCI’s storage to your self-hosted runner as “Network Egress”. and the Storage is also charged Persisting Data Overview - CircleCI
You are free to use your own storage/network mechanisms. It just won’t be as trivial as the built-in functionality.