From what I hear, the logistics to build and maintain a quality Facebook game properly are not something that is easy to manage with a small team.
Despite what is common perception, it is outside the realms of bedroom programmers to build functioning social games on the level of Farmville. You might be able to make something similar, but good luck keeping it up and running and actually getting your money back.
It is a bit like the myth that was precipitated about mobile development being a boon for start ups and bedroom programmers a few years ago. This has only become realistic recently with the iPhone app store cutting out the middle man and making wide distribution realistic option for smaller teams.
Be realistic – you are going to need money, lots of it, and a couple of dozen employees (not just designers and coders).