I would be actually happy if Google crawled my site every day (of course it also matters the fact if you can afford that much of bandwidth), as Amross advised you on robotstxt.org you could find your solution. But i am not sure if just BLOCKING the bot would actually be a Solution.

You could register on Google for free, from there, you can chose the speed and how many times the Googlebot should crawl your site. Take some times (if you have) and test that feature (personally i haven't tested it).

Cheers.