Can confirm, paid mentions for 1000-3500 a pop.
I used to work at a content marketing agency, the founders pitch themselves as marketing experts and pitch articles, basically submitting and pestering the submission staff of tech crunch, Forbes, fast company etc. until they were granted contributor status, From there, ghostwriters wrote articles and include mnetions and links. These articles typically would mention clients were we courting ( smb, promising startups, fin tech), and PR clients who paid for these articles in a PR package . We had about 4 active contributors in our office of 20. We had the least amount of overhead in this department I think it kept the rest of the place afloat.