Hiring an existing team in-house (Score 1)

I would not suggest outsourcing something like this unless you were prepared to do a complete re-write with an in-house team if the initial release seems successful. For reasons that many have already stated, it doesn't work well in the long run. In the short run, you could get your first release out and see if there is enough interest to keep going. But you will want to bring development in-house if you want the product to grow. The fastest way to get going is to find a lead developer you like and see if s/he can bring a team, or its nucleus, with him/her. Then you get a mature team with incentives aligned with yours.