Neilsen: Users spend most of their time on other sites.
Provide all the information users need. Fail this and you’re inviting users to leave, which they’ll do so soon enough anyway. In particular, your site should show prices (violating this guideline was the #1 Web-design mistake of 2002). If users need to search out other websites to get their questions answered, they’ll likely discover alternative solutions to their problems elsewhere rather than explore your site’s options. The more clumsy and less informative a site seems, the faster users will abandon it.
From Cross Site Behavior.