Look at the Location header in the response. I see the Location header in my curl -v query.

Never mind - the redirect location is pointing to an error page.

Perhaps lwp (and curl) are not allowed clients? Compare the headers sent to find the differences. Check the ToS on Digi-Key's site, as they may not allow mechanized searches.

You may not use any robot, scraper, spider, or other automated means to access or gather the Content from the Site, or mirror, co-brand, or frame the home page or any other pages of the Site on any other website or web page. For purposes of these Terms of Use, “co-branding” means to display a name, logo, trademark, or other means of attribution or identification of any party in such a manner as is reasonably likely to give a user the impression that such other party has the right to display, publish, or distribute the Site or its Content. Competitors and third party aggregators may not connect "deep links" to the Site, i.e., create links to this site that bypass the home page or other parts of the Site without the written permission of Digi-Key. This prohibition is not intended to restrict the non-commercial activities of individuals.