it completely depends on the "product" that you have in mind. it can be from a couple of hundred bucks to millions of dollars.

so if you actually have an idea (not just asking random questions) then you have to first think it through and then put it on paper. then do something like patenting to protect your intellectual property (only if you want to go that way) then you can publicly introduce your idea and ask for investors in your product and raise money that way.

of course this is only if you want to be honest. there are scammy ways of raising money and delivering nothing too. like running a shitty ICO and becoming millionaire just because you created a website