Best RSS for Craigslist?

I read somewhere that u can keep an eye on great deals or specific items that you are patiently waiting on for the right price by tracking it by a RSS feed program. For example: U want an ipad mini and all the ones u see used go for $300 but u are wanting one in the $250 range. U RSS it and when one is posted for that price or less it alerts you.

Has anyone done this and so how and what RSS feed software do u use? Thanks.