Site recipe suggestions for a movie studio asset management site?

I've been asked by a large local movie production company _{(*ahem* Wellington, New Zealand ;)} to help solve their inventory management issues.
These are things like generators, lights, scaffolding, props and untold miscellanea that have to be moved between warehouses, sets and teams on a timely basis.
So I'm looking at an equipment reservation system to ensure the right people can get access to the right things (and studios) and it's not out on the job somewhere.

In the meantime the also need to start with an inventory system, full-stop. ...Although I'm trying to encourage them to sort out a commercial off-the-shelf package for that. Internal warehousing is not really a job for a website.

And they want support for an ecommerce hiring out system as well where other companies or units can book assorted gear for days or weeks also.

I'm guessing there will need to be a sign-off layer as well, so units can put in requests but only production managers can OK them.

And there will also have to be travel time built in to some of these orders!

Quite a challenge!
I don't expect anyone to solve it for me ;-) and I'm prepared to rewrite lots of code glue to get what I eventually want, but my question is:

What do you think are the building blocks I should begin with and integrate with?

• Should I build hire periods on event.module? Do you think it's possible to extend it to handle durations and become an ecommerce product?
• Is location.module appropriate to model where things are or where they are wanted?
• Is it possible to keep a running tab with ecommerce rather than a set of purchases?
• Has anyone done, or even seen anything like that before on the web? Drupal or not? Links?
  resource_conflict is all I see.

Any modules I should learn from?

Any brainstorms out there?