When you're looking for potential funders, one way is to search for organizations or agencies with a mission that is similar to yours and visit their websites. Usually, their biggest funders will be listed somewhere on the site, and might even have logos of the funders that you can click on and go directly to (it's unlikely, but possible). When you visit the sites of the funders, you want to go to the page that lists what their giving parameters are and make sure your project is a good fit. Sometimes, there's a personal relationship or some other non-traditional factor that allowed the funder to go outside its parameters to fund an initiative. In other words, just because a funder gave to an organization similar to yours, doesn't mean the mission of your organization is technically within the guidelines, and you'd be wasting your time applying.
If following the leads of individual foundations doesn't pan out, be sure to check out any corporate affiliations. Though you might not have the exact same corporation in your area, if another organization forged a successful relationship with, say, a construction company, perhaps you should explore how a local construction company might be a good fit for you.
Similarly, if a community foundation or United Way funds an organization similar to yours, perhaps you should explore your own community foundation and United Way.
Google (and other search engines) as well as Charity Navigator can help you locate organizations that have a mission similar to yours.