That's interesting. But I think it's a mistake to focus on relying on price to prevent abuse at scale. The use case for abuse of this technology is in highly targeted frauds, not broad-spectrum scams like insurance robocalls. Additionally, this will be zero deterrent to deep-pocketed actors like political action committees that generate fakery to influence elections and the like.
I'm trying not to be reflexively dismissive, and I know the technology is evolving so fast that your individual company can't necessarily pre-empt it, any more than an email software supplier is responsible for the existence of phishing. But I work adjacent to the security space (studying violent extremists) and I can think of a ton of ways to abuse this where economics would be absolutely zero deterrent.