As some of my readers are not from area’s that use CraigsList this is intended for the US readers.
I have two main apps I use for searching CraigsList, someones trash is another mans gold (or just a sweet deal)….
But the main problem with CraigsList is you don’t have time to sit and search.

CraigsNotifia is by far the best Android App for that purpose.
Simply put in your search terms (as many as you want but i’d say stop at 10-12) with price filters and that app will find your item when it shows up and notify you on the spot.

Price –
Free with Ad’s (works amazing and I bet they make more money from the Ad’s)
Donation Version – $9.99 (Same app no Ad’s)

Stay ahead as you get notifications when new items are registered on craigslist.

* Create templates to respond to craigslist ads.
* Search multiple craigslist regions.
* Receive Notification when something new is posted.
* Favorite craigslist ads.
* Browse all craigslist categories.

CraigsNotifica provides an advanced interface for reading Craigslist RSS feeds.

** Update 12/18/2012**
For you that are looking for “Where is Craigsnotifica” seems like the application was pulled and now has a new name “Notifications For Craigslist”
Linky – Clickme