18922 craigslist search bot

I want a bot to search craigslist (the US cities, or all of them), the bot will search through jobs and gigs section for a keyword I specify in my admin. Then the bot is to copy the title, the url of the results, and the email with the post into a database. I want to be able to see posts that have been posted in the last 48 hours. After that it can purge the database. The script is to autorun every morning at 3am. No password/logins necessary (I will just password protect the entire directory/subdomain it will run on). Don't want this bot to get blocked from craigslist, so it should only run once a day. To add new cities to the list it searches, we should be able to enter the city into a form in the admin section. The output should be simple. this is to be done very soon.