Very much like: http://telecraig.com/ It searches all of craigslist and pulls only jobs that feature the word telecommuting in them and the search term entered into the box.
If you could point me in a location where Craigslist allows for searches for all of their combined cities I *might* be able to help within your budget. . . Otherwise, I know right offhand how it could likely be done, though it's a whole lot more complex & I would assume that even coders from outsource countries would charge more for the complex method than you're offering. edit: I code in perl/cgi & my method would require a special module (not present in many paid hosting companies) & a MySQL database.