There’s a piano inside a bookstore. It’s available for anyone to play, including you.

If you do that, you won’t need to buy a piano, but the trade is that everyone hears you play, practice, or perform. They might like it, they might not. They may be waiting their turn. 

You’ll need to develop a thick skin to play longer than a few minutes, and the flexibility to give up your seat when someone is waiting. You also have no control over whether or not the piano is there tomorrow. That’s how practicing in public works.