Does anyone have experience with a site where the content is rapidly producing new pages and removing old ones?

For example one day there maybe deals for a certain product combination and so a page exists. The next day it wouldn't exist and so would 404. The majority of the site will remain solid but a lot of tail end pages will be created and removed each day.

Ive been thinking of a few possibilities:

Option 1) Allow 404's but update the site map regularly with the changes.
Option 2) If a page is created it should exist forever, just don't link to it throughout the site (and remove from the sitemap?). In the future the page might become valid again.

What would you suggest as the best practice?

Many thanks,
Matt