FTA:

> Nobody wants to wake up to an email sent at midnight warning about a budget limit and find that, while they slept, their rogue service had consumed several hundred (or several thousand) more dollars of usage.

Monitoring and a circuit breaker. If you are given the tools, make your own heuristic and flip the breaker yourself. Don't let someone else turn it off, and be hostage to their process failures for getting it back on. By self-selection, if you are a hard limit customer, you are not front of their service line.

> An argument against this is that businesses don’t want their hosted applications to start throwing errors because some budget was exceeded. I expect that most businesses and individuals would prefer errors to a surprise $10,000+ bill.

Based on a career serving the Fortune 50, CTO for trillion dollar bank, etc.: "No." Assuming actual business is being done by the machinery in question...

The lights must stay on.

Cost management cannot shut off the enterprise. Cascading costs, even before reputation, are incalculable.