BayLeaks partnered with the San Francisco Bay Guardian, before it went under. My co-founder was a long-time San Francisco journalist and I was able to collaborate with her on several stories and get introductions to journalists and editors for stories I was doing independently. But of course, you could always just investigate stuff, find the email of an editor at an outlet that seems to publish that kind of thing, and write an email pitch. If they're interested, you send your story, and they'll tell you how much they would pay to publish with them.