The cash flow forecast is another modern day essential for starting and running a business. So do a business plan and a cash flow forecast before you start. Having done these you may not want to start. I'm sure I'll sell lots. The business plan and cash flow forecast are parts of the equation.
Market research is another.
If they think your idea is a good one. You need outside, impartial advice. This assumes that you have already identified who your customers are going to be and if you haven't then you should. Yes of course you can. The more help and advice you get before you start the better.