An active tumblr account with 10k targeted real followers in an adult niche would probably be able to pull in more than $35. If this was built organically you could probably get double that. If it was built with bots, probably less.
Look at it this way: Let's say someone with an adult site bought it, continued doing what you are doing, but made some extra posts linking back to their page. To an affiliate looking for a free signup to MFC or something, they'd have to get 30-40 people to do it to make it worth their while. A social media intern at a production company would only ever have to get maybe 1-2 people ever to have it more than pay for itself.
There would certainly be value there, and even moreso if your followers are engaged.