I'd like to search Amazon.com for products that Amazon sells without having to see all the third party merchants products.  I've tried using some userscripts and some chrome extensions that claim to do the job but none of them seem to work.  I prefer Chrome, but I can use FF for the searches if someone knows of a FF fix that actually works. 
How can I filter Amazon.com results to exclude 3rd party merchants?
filter;firefox extensions;google chrome extensions;userscripts
Amazon Advanced Search Chrome ExtensionAmazon Prime Search