In almost every case, inter-account and inter-AZ transfer will incur the same pricing as egress, especially if it travels through an IGW.

In our internal testing, it appears that AWS often applies the egress pricing twice, both when leaving the AZ where your instance(s) are located as well as again in the region where your customers are, after traveling through the AWS internal network; the first is an inter-AZ transfer, and the second is the actual egress from AWS' network.

So, it appears that the egress fees are nearly always not merely the oft-cited 8,000% greater than competitors, but twice that. AWS is not very transparent about this.

Understatement of the year: "Data transfer charges are often overlooked while architecting a solution in AWS."[0]

0. https://aws.amazon.com/blogs/architecture/overview-of-data-t...