"Business model? We don't need no stinking business model."
 
It's simple. Start with expertise. Do a lot of different things well. Find small economies created by using state of the art equipment. Assemble a pool of talented people (who you only pay when they actually work). Then work hard. Do not hesitate to refer a client to a strategic partner who can do something better or more affordably - and they'll do the same. Make sure everyone's happy, and it always pays off.
You'd be amazed how well this works.