I would like to have all cost and ressources used of each IAM users. 
Unfortunately, i can have only the cost of my master account. I know that i can create a organization and set OU and users AWS account to have a detail and record each events, but the ressources used by 'users' are used only for my application, i don't need to have real account, and i can't automatises all deployements if i must set password and credentials manually . 
One solutions also is to create CloudTrail and Cloudwatch to record each events services but i found this 'too heavy' and i will need to calculate myself the cost because it only get the datas which are used. 
I would like to know if they are exists others systemes to do that in preference with boto3.
Thank you for your responses. 
Have a nice day/night.
Costs are not easily associated back to "users".
AWS resources are associated with an AWS Account. When a user creates a resource (eg an Amazon EC2 instance), IAM will confirm that they have permission to launch the resource, but the resource itself is not associated with the user who created it.
You would need to add tags to resources to have more fine-grained association of costs to people/projects/departments. These tags can be used in billing reports to provide cost breakdowns.
How to get a summary of ressources/cost used per IAM users in AWS?