I would advise staying on Wikia or just cutting your losses and moving over to ShoutWiki or Wikii and building your Wiki up there before you try to spend a lot of money going independent. Wiki farms aren't inherently bad in what they can do, but they are not viable options for NIWA Wikis. Wikia is probably the last nurturing and the most stifling, and you'll have the hardest time moving away from them.
Of course, if you want to become independent, we can help you, and will also do our best to nurture your Wiki along the way.