I agree with the majority of what's already been said on this thread.
I'd also stress this point: immediately hire a strong developer that you trust to review his work. If you're a non-technical person, even if he shows you a demo, checks into GitHub or another source code repository and starts providing you with regular check-ins and updates, you won't be in a position to effectively review his work. You need to find someone you trust who's an expert in the technologies that you're using and have them evaluate the work that is being produced.
This is a good general rule of thumb for any kind of outsourcing, and especially off-shoring. If you've got the skills to review the work, great, if not, you must find someone who does. Otherwise, it's a total crap shoot.
The senior dev / architect will cost you more, but you shouldn't need too many of their hours. This person combined with cheaper, more junior devs can be a decent, cost-effective way to get things done.