Everybody may already know this, but hopefully it will be of use to someone.
enter "topic site:craigslist.org" into Google or whatever search engine you use, for example "1965 GS site:craigslist.org" turned up a pair of GS consoles for $100 in CA. "Topic" can be anything, and always include "site:craigslist.org" in the search term for it to look everywhere.
Note that some search engines keep stripping off the "site:craigslist.org" in between searches, so you might need to keep retyping it to avoid a wider internet search.
Happy hunting,
Steve
