Yep - that's exactly it. Setting up the infrastructure to handle large, web-scale content analysis is the real challenge. (Shameless plug alert) That's why we setup 80legs: to help everyone not called Google/Yahoo/Microsoft to have comparable capabilities when it comes to this.
But I think that once you have enough customers the cost of 'crawling' goes down for every new customer you sign up because you only need to crawl a page once and you can sell the crawled result to many customers. Or do I misread your model and is every page crawled over and over again for every user ?
