Are you wanting a "real product" or a business?

Idea < product < app business

Developing the "product" itself will come with financial costs. Hire a team (hopefully the right team). Pay their fees. And you'll end up with the product (with varying degrees of quality, compatibility, user experience, value all depending on how successfully you selected the team and how they executed on your idea).

Now what.

You have an app.

Neat.

You are in the mix with 2.2million apps in the world (january 2017, total apps in app stores) that someone can find, download, install.

Now what?

What's your marketing plan?

How will you increase downloads? Usage?

How will you later monetize?

And how much will all THAT cost you? In team, time, energy?