AWS already give you intelligent tiering for this, it's a very nice product but it's also just a nice way of hiding the same fees. Your $0.004/GB becomes $0.023/GB on first read for 1 month then $0.0125/GB for 2 months, so the average cost of storing it over those 3 months becomes $0.016/GB, and that's before considering monitoring fees
You could also implement tiering yourself, depending on your workload of course. If you know you're storing objects for long-term archival reasons (or backups), you could opt for using S3 Glacier Instant Retrieval at $0.004/GB.
