i'm pretty new so I haven't looked around the sit a lot yet, so I don't if you guys know about this. but i found this on a sears site awhile ago
SearchTempest.com searches all craigslist nationwide from one search. it is very tunable
*just don't be too specific in the search or you may not find what you're looking for e.g. : say
"ford lgt" not "ford lgt195 tractor" too many words doesn't always get better results you may have to look through a few more , but i've found some posters don't always describe correctly. you may miss a good deal.
Oh yah it includes ebay postings as well