We strongly suggest you concentrate on your strengths (presumably designing and marketing) and leave the grunt work to someone else. Source around.
Let us look into this idea.
- Heavy and expensive. You may need thirty to one hundred dollars and three-phase power. You will also need a decent oven (the batch type ones are not great, especially for Pb-free) and a decent stencil printer. You will have to keep all the various chemicals in stock and fresh
- Setup time.
- Process Control. You still have to manually inspect the boards and do any necessary rework, you are responsible for controlling the processes, maintaining the machines and ordering spare parts etc.. Often there will be parts that have to be manually attached later because they are incompatible with some part of the process (too tall to go through the conveyor oven, through-hole for mechanical or cost reasons etc.)
So consider these problems before deciding to do the SMT by yourself. Good luck.