Asking the right questions! EC2 prices absolutely depend on the Region you decide to spin up an instance in, and these vary due to a number of different reasons, some of which are beyond the control of Amazon.
Reasons like supply and demand, cost of operations, competition with other cloud providers in that location, government policies — and undoubtedly several other factors that AWS doesn’t go into.
The cost of services and resources in Amazon Web Services varies from Region to Region. Add to this the fact that not all Regions have all the services available to them due to rollouts, or hardware logistics at any given moment, means that you will have to plan carefully if you want to span your cloud presence across the globe.
In terms of pricing, though, the situation is much simpler.
Being that US East 1 (North Virginia) Region was one of the first Regions that was up and running, it is pretty much the cheapest Region in AWS. In fact, the cloud giant refers to it as US Standard. In general, it also has the most services available on the platform, as Amazon usually prefers initial rollout here.
As a rule of thumb, US pricing is usually the cheapest, although this is depending on the service and instance type chosen.
Things get more expensive in other Regions, though most of the time the difference is nothing radical.
At the end of the day, cloud is all about networking. And the success of networking web applications and content is how well it is delivered to users. It does not matter whether this content is as small as an image that weighs in at 1 byte, or a custom software that requires 100 gigabytes of download, you will have to make a decision of where and how you want it all stored and delivered.
The picture becomes a lot clearer if most of your users are located in any of the locations where AWS has its Regions. But if your userbase is scattered across the globe, then those that are located further away will feel latency when accessing your content. Not to mention, the problem will exasperate if more users are accessing the content at the same time.
This will require you or your organization to host your sites in different AWS Regions and then perform syncs across those servers, which is a task that is complicated in both design and management.