To build a backend and database, you usually need a team that consists of backend developers and a database administrator at the least. Other roles might be required depending on the complexity of the project like DevOps engineer, security specialist, etc.
Here are some general assumptions:
- Backend Developer: $50/hour
- DevOps engineer (optional): $55/hour
- Cloud hosting (e.g., AWS, Azure): $10 - $1000/month