AWS offers two popular caching services: Amazon ElastiCache and Memcached. While Memcached is a protocol that ElastiCache supports, for simplicity's sake, we'll discuss the price differences between using Memcached through ElastiCache versus managing your own Memcached instances on EC2.
Amazon ElastiCache is a fully managed caching service that provides support for Memcached as well as Redis. Pricing for ElastiCache is primarily determined by the node type that you choose to run. Each node type comes with different amounts of RAM, CPU power, and networking capabilities - for instance, prices per hour for a cache.r6g.large node in US East (N. Virginia) is $0.158.
In addition to the cost of nodes, other factors such as data transfer costs or additional features like backups or multi-AZ replication can affect the total price of running an ElastiCache cluster.
You can find detailed information about ElastiCache pricing here.
If you're managing your own Memcached instances on EC2, the main costs you need to consider are the EC2 instance costs and any storage you might need if you're persisting your cache to disk. Just like ElastiCache, EC2 instance costs vary greatly depending on the size and type of instance - for instance, a t3.medium instance in US East (N. Virginia) costs $0.0416 per hour.
In this case, you also have to account for the maintenance and management overhead, which although doesn't directly translate into a monetary value, it still represents resources that your team has to spend.
More details about EC2 pricing can be found here.
Both solutions have their pros and cons, and the decision between them depends not only on the pricing but also on your specific requirements and constraints.