Depends if you use exactly 11GiB a month, no more no less. Many people use a hotspot more one month, less another month. 11GiB for $70 is absolutely a great deal for some people, but not most people.
We don't change the emitter, the listener changes the SNS config. The emitter publishes to SQS under a certain topic. Listeners that interested in that topic subscribe to it by changing the SNS config, basically saying "give me a copy of those events too and put it onto my own queue". SNS copies the messages to every queue.
We have considered stuff like RabbitMQ. They would be excellent solutions too and we are working on a part of our architecture with MQTT/protobuf (more on that later, I'm sure). We went with SNS/SQS because we don't have to build a cluster with that. Building clusters is hard and Amazon takes care of that. Since we were already using a bunch of AWS products, this was a nice fit and we're quite happy with it.
Authentication is a good idea for an article too. Thanks :)