That's a huge question that can only be answered with the "depends" word! But a good way to start is to look at the market. Doing a market analysis to give you an idea about the demand and competitors would be a good way to start.
Then look at your production costs - is this a product you can license, resell, or do you need to create from scratch?
Then, of course, the administrative, setup and foundational needs will be front-loaded, so be prepared.
That's where I would recommend you begin, and that will help to start framing the idea of whether you are talking about $1MM, $100k, or $1k...
-JL