It seems there are many approaches to deploying WordPress on AWS
For example, there are cloud formation templates available. When I used these, they didn’t quite work out of the box, and I had to change some permissions on the Linux file system when it came to doing things like uploading media.
Given that I was going to have to mess around with Linux, my next approach was to follow a walkthough on the AWS site. You install a LAMP stack manually, then install and configure WordPress manually. Its a good learning exercise.
Another option is using LightSail, if it fits your needs.
In the end, I went for a Bitnami WordPress AMI from the Marketplace
For a low cost, low volume site, at the time of writing this site is running on a t2.nano, at less than $5 a month. You could use a t2.micro to be free-tier eligible if your account is still in its first year.
Later I might go for a t2.micro spot instance:
Relatively stable at $0.0038 for 3 months, that works out at $2.73 a month.