They charge a premium for the searching, but if you really need information from a file available only on a large vendor's service, this can be a reasonable option. Some services have substantial searchable databases available. The ability to send and receive Internet e-mail, read Internet news group messages, and to browse Internet Webpages has become a key component of the service to subscribers of commercial information services. This is an area where careful shopping is required. Compare the cost of e-mail sending and receiving and browsing time.
Some services are better deals in one area, others are better in another.
This is an area of high competition and constant change, so be sure to have a good list of questions before you decide which service to subscribe to. The content submitted by the publications and services is generally high, since they are selling this as a commercial product. The organization is thoughtful and consistent. Quality standards are more rigorous. These services are like mini-World Wide Webs.