AWS S3 costs for when AWS EMR uses it
The S3 pricing page says
Transfers between S3 buckets or from Amazon S3 to any service(s) within the same AWS Region are free.
Based on this, I believe EMR to S3 data transfer has no cost.
S3 Request Pricing
Note that S3 request pricing still applies. That will change over time, but right now it's
- PUT, COPY, POST, or LIST Requests: $0.005 per 1,000 requests
- GET, SELECT and all other Requests: $0.0004 per 1,000 requests