I think the killer feature here is supposed to be voice cloning, which IIUC Google Cloud offers only as a custom enterprise thing that takes weeks (which suggests that it's not fully automated).
The most expensive Google Cloud option[1] gives 100,000 bytes free per month. This gives 10,000 chars per month.
The next tier is $5/month. With Google that gives you over 130K bytes.
And that's the most expensive model. With the moderately priced model $5 gives you 1.3M bytes.
With the cheapest model you get 5.25M bytes.
I use their service, so I know the economics. I pay nothing per month because I use the intermediate model, and I don't need more than 1M bytes per month. Switching to this, I will have to pay at least $5/month for a voice that's not really any better than Google's.