I've had success with OwnCloud as an opensource replacement for Dropbox. Buy a VPS from DigitalOcean or RamNode, and you get a more libre and cheaper Dropbox that you can control at all levels.
However. The privacy level is around the same as on Dropbox. Your hosting company can read your files. And the average Joe probably does a worse job securing his VPS then Dropbox does at securing theirs.
OwnCloud is really aimed at small companies or tech users. Average Joe can't really set up his own OwnCloud instance. Way too technical.