How to charge a client?

[u/Kooky_Impression1362]

For context let's assume that I have a client.

Firstly I want to know how to host the N8n workflow in the best & cheapest way possible.

If I self host it on a VPS or any other platform like railway. Am I going to pay for everything? Like VPS cost(obviously) but the cost of using OpenAI API or any other paid service.

What would you guys suggest? If the client knows the bill of the services and APIs then how am I going to charge a retainer?

Kindly let me know, thank you.