This seems like something you could build over a weekend. I'm excited to see an open source alternative for this.
EDIT: Folks, if you're truly large enough to benefit from vantage, please talk to your AWS/GCP/Azure rep and work with them on deciding what you should do for committed usage. There are a lot of ways to save money on cloud costs, and they all start with a conversation with your cloud provider. If you don't have enough spend to have a cloud provider rep, vantage isn't going to save you that much money.
I also think it’s showing extreme naïveté when it comes to the fallacies of “myths programmers have about X” where X in this case is billing. Billing and money is hard not because of the technical aspects of moving 1s and 0s correctly but because it’s a socially mediated system with a lot of messy things that tend to require humans.
the value of what Vantage is building is not by solving a technical challenge, it's by solving a marketplace/network effects problem (something that is much harder to do)
EDIT: Folks, if you're truly large enough to benefit from vantage, please talk to your AWS/GCP/Azure rep and work with them on deciding what you should do for committed usage. There are a lot of ways to save money on cloud costs, and they all start with a conversation with your cloud provider. If you don't have enough spend to have a cloud provider rep, vantage isn't going to save you that much money.