There are multiple ways you can save money and utilize different types of resources and services based on your budget and use case.
AWS documentation is the most clear of any cloud provider I have worked with, and for each service they give you a clear idea of what you get charged over time.

For future reference, you can also set billing alarms to alert you when your costs go over $x.
When your costs reach that level, you can go to your billing dashboard and see exactly what services you are being charged for and take the appropriate action.