I'm curious about this too, especially since OP says they'd like to continue scraping. I've heard of other people crawling craigslist getting banned pretty fast and even one site getting slapped with a lawsuit [0]. (Which looks like was not entirely successful for craigslist.)

Craigslist has even taken some measures to get their users to assign copyright of the content over to craigslist themselves [1].

[0] http://venturebeat.com/2013/05/01/padmapper-craigslist-3taps... [1] http://www.on-site.com/what-you-need-to-know-about-craigslis...