Two reasons, potentially:
1. Principles.
2. If you find another site that gives immediate pricing, you can use it for any subsequent purchases in a similar domain, or they may also be more respectful of your time in other respects (e.g. support), saving time in the long run.<p>Besides, it stands to reason that googling around for a few more minutes is less time and hassle than waiting for one or more e-mail round trips with humans in the loop for the quote process.