Hi,
I will need something like that as well, for a new site I'm doing and here is what i will do:
First part module:
kind of "event" module which will let the admin display what, where and when is free, busy, partial free, etc".
I will probably ask admin to create a google calander, make it publish and I'll Embed it into the site.
Second part module:
Kind of contact form.
I will use taknology.net module for that because among other great, new, unique, innovative concept and features, it lets you create a beautiful "date picker" control.
So it won't be full automatic, but admin can update the event module once a day or so, or after he gets cash in other scenarios. :)