Durable Objects are the coolest thing I have seen in a while. Code and its data locked away together, frozen when not in use, but ready to go in milliseconds when a request comes in. They are so damn useful.
A $34K bill with Durable Objects implies they somehow made 227 billion requests in a month. Sure, if that's the kind of traffic you're serving, your bill ought to be $34K! That's 87,000 per second!
They're pretty cool indeed, just pretty risky.