Thanks for the detailed writeup. I think projecting future costs would be hard but someone pointed out in previous comments that service specific rules ( EC2, S3) etc could be more realistic.
Also what do you think about AWS Cost Explorer API? It looks like it can provide monthly/daily charges and we can build rules for customer tolerance, like you mentioned.
Also what do you think about AWS Cost Explorer API? It looks like it can provide monthly/daily charges and we can build rules for customer tolerance, like you mentioned.