I have a question about the costs of versioning in Amazon S3 that don’t seem to be present in the guide. There is a cost for every PUT/POST, but for versioned objects(especially when you keep older versions in alternative storage such as glacier) does each PUT/POST cost 2x the PUT/POST cost, one for the new version then one to move the old version to glacier?

You can refer to FAQ page: https://aws.amazon.com/s3/faqs/?nc1=h_ls

Q: How am I charged for using Versioning?

Normal Amazon S3 rates apply for every version of an object stored or
requested. For example, let’s look at the following scenario to
illustrate storage costs when utilizing Versioning (let’s assume the
current month is 31 days long):

1) Day 1 of the month: You perform a PUT of 4 GB (4,294,967,296 bytes)
on your bucket. 2) Day 16 of the month: You perform a PUT of 5 GB
(5,368,709,120 bytes) within the same bucket using the same key as the
original PUT on Day 1.

When analyzing the storage costs of the above operations, please note
that the 4 GB object from Day 1 is not deleted from the bucket when
the 5 GB object is written on Day 15. Instead, the 4 GB object is
preserved as an older version and the 5 GB object becomes the most
recently written version of the object within your bucket. At the end
of the month:

Total Byte-Hour usage [4,294,967,296 bytes x 31 days x (24 hours /
day)] + [5,368,709,120 bytes x 16 days x (24 hours / day)] =
5,257,039,970,304 Byte-Hours.

Conversion to Total GB-Months 5,257,039,970,304 Byte-Hours x (1 GB /
1,073,741,824 bytes) x (1 month / 744 hours) = 6.581 GB-Month

The fee is calculated based on the current rates for your region on
the Amazon S3 Pricing page.