Search services are now ubiquitously employed in searching for documents on the Internet and on enterprise intranets. This research develops an economic model for comparing search services based on a user?s information requirement in a decision making scenario. The model considers the noise effects of querying, search and filtering of results. Different search engines might return different results for the same query based on the characteristics of the search engine?s algorithms and the extent of captured data. Users are thus faced with the selection of a search service in order to minimize cost, reduce uncertainty, and maximize the benefits derived for their efforts. A methodology for comparing search services based on the model is presented. This comparison can also be used by search service providers to enhance alignment between their objectives and that of users as well as for pricing of their products and services. A preliminary experiment comparing three popular search services is used to illustrate the model.