I wrote a small crawler for Craigslist making absolutely sure that it obeys the robots.txt rules.
Sure enough, after a few hindered of requests my crawler got banned.
Doing a simple search at Google, I can see from the results I get that CL is happily allowing Google bots.
I strongly believe that this discrimination against small players is highly unethical, but my question is, is it breaking any laws or maybe anti-monopolistic rules?
That said, you've already given the solution to your problem yourself. Instead of crawling craigslist, crawl google instead.