Alerting Clammer to costs of batch runs

[owencking]

Because

As a Clammer,
When I have defined a batch and I am just about to "Start" it and I am warned that what I am about to do may cost money,
I am given some very rough estimate (either in dollar amount or just relative to the cost of other batches) of how expensive the batch would be to run.
Rationale: Some batches will be larger than others, and pipelines vary a lot in terms of how computationally intensive they are. It would be easy to be about to run a batch that was crazily enormous. It would be very helpful to know how enormous.

Done when

The Chowda interface presents some representation of the expense at the appropriate moment.

Additional context

A rough estimate, or even a bit of information that the Clammer can use to make a rough estimate, would be the most valuable thing.