The font is not cheap either*.
When you can barely get people to pay $0.99 for a industry leading app, how on earth can you justify paying so much $$ for a font. I mean switch to the closest google / open source version and call it good enough.
It's $300/year from what I can see. Not free, but if you think it's a valuable part of your design, a small cost, unless you just don't have a viable business in the first place.