A few electronic part vendors which hide their search string:
http://www.arrownac.com
http://www.powell.com/prod_search.php
http://www.futureelectronics.com
German sites:
https://www.rutronik.com/webgate/index.php
http://www.arrowce.de
Can they be included in Mycroft?
I found http://www.arrownac.com
http://app.arrownac.com/aws/pg_webc?s=p&event=1009&appid=nac&application=SEARCH&search_token={search_term}
and http://www.futureelectronics.com
www.futureelectronics.com/en/Search.aspx?dsNav=Ntk:PartNumberSearch|{search_term}|1|,Ny:True,Nea:True
How you find the search string when the URL does not echo it?