We have found that a good place to start is usually right in your own backyard. Many large companies such as Target (Target + Blue grant), Office Depot, Build a Bear and Wal-Mart for example, have grants available that are not difficult to apply for, and if you are lucky enough to have one of these stores in your community, these may work for you.
In addition to grants, a great way to raise funds for prevention is to involve the youth themselves! Let local teens design a walk /run, and have them meet with the local newspaper and media to generate support and coverage. City/County governments and the media love to support positive actions by young people.