Comment by melted

Microsoft spends over $1B/yr on maintaining and improving Bing. So yeah, search does cost a fortune if you want to do it reasonably well without relying on others for results. Not only do you have to crawl the web (with different frequencies depending on predicted frequency of content update, etc), you then have to rebuild the index continuously, with reasonable latency. To do all of that, you have to have indexing infrastructure, which in turns requires storage infrastructure, high performanc data processing infrastructure (Hadoop ain't gonna do it, ask Yahoo as to why), which in turn requires high performance networking (or your mapreduce-like workloads will collapse under their own weight), your own datacenter, and your own army of machine learning researchers, systems engineers, hardware engineers, networking engineers, devops, quality engineers (people who improve your scoring function), human eval, etc, etc, etc. If anything, $1B/yr seems to be quite low.