One of the tricky things is making sure that you're not duplicating things you've already backed up. The way I handle it is through a combination of date ranges and tags.
The article says it costs $.40/mo to store 400GB on Glacier. Looking at current Glacier pricing of $.0036/GB, that should actually be $1.44/mo. I realize an additional $1.04/mo isn't much but the number is off by a factor of 3.6x so I'm just trying to understand. Also, if you're willing to spend a tad more, the 400GB could be stored on Backblaze B2 for $2.4/mo but egress is free!
It depends on the region and which Glacier product you choose. I think your pricing of $0.0036/GB is the cheapest I've seen. However it is for the 'Flexible Retrieval' option. 'The Deep Archive' option is $0.00099 and thus 39.6 cents a month. This rounds up to the $.40 figure provided in the article.
https://gunargessner.com/takeout
One of the tricky things is making sure that you're not duplicating things you've already backed up. The way I handle it is through a combination of date ranges and tags.