The custom package search of simpleSearch is nice but rendered useless if you don't have any connection to a resource
[i]joinCriteria[/i] - The SQL to join the table you want to search and the modResource table. Your table must have some connection to the Resource it's on (otherwise SimpleSearch won't know how to load a URL for it!)
I am using MIGX (packages) and simpleSearch with a faceted PostHook
https://rtfm.modx.com/extras/revo/simplesearch/simplesearch.simplesearch/simplesearch.faceted-search-through-posthooks.
Disadvantage can be, in my case it was on purpose, that it is not integrated with the rest of the search results.
Redhen posted an example of a hook just recently here
http://forums.modx.com/thread/98382/how-to-search-website-for-product-names-on-dynamically-created-pages#dis-post-532255