I need to run a web crawler and I want to do it from EC2 because I want the HTTP requests to come from different IP ranges so I don't get blocked. So I thought distributing this on EC2 instances might help, but I can't find any information about what the outbound IP range will be. I don't want to go to the trouble of figuring out the extra complexity of EC2 and distributed data, only to find that all the instances use the same address block and I get blocked by the server anyway.

NOTE: This isn't for a DoS attack or anything. I'm trying to harvest data for a legitimate business purpose, I'm respecting robots.txt, and I'm only making one request per second, but the host is still shutting me down.

Edit: Commenter Paul Dixon suggests that the act of blocking even my modest crawl indicates that the host doesn't want me to crawl them and therefore that I shouldn't do it (even assuming I can work around the blocking). Do people agree with this?