By 6 people, do you mean 6 developers? If so - the market rate, at $166,667 annual per developer, is extraordinarily higher than I thought. That seems a bit pricey for a developer working at a scrappy startup.
I'm sure there are other costs some optional, some not. Depending on how lean you want to run you can have a very low overhead.
It also depends on what level of developer you are hiring.