I would pay for advertisement on 4chan. It would be perfect for recruitment, especially on the more arty boards like photography. But it would take at least:

- the possibility to buy small packages, partly because the companies who are big enough to buy the big package are the ones who care most about reputation

- the possibility to define your audience, at least by: board, keywords, country/city of origin

None of which are possible now: http://www.4chan.org/advertise/