What if you made the app cost $0.99 and that included the first postcard?
You get far, far fewer purchases, but each purchase is a far, far more qualified customer, plus, you can almost break-even on the one-and-dones, and you may make enough money on the breakage to make it tiny profitable.
I get that tiny profitable isn't a VC's goal, but for a side project that's dying anyway, this might make the runway infinite, which you could use to rattle around and maybe find a winning model, or just let it run and not cost you much.
You get far, far fewer purchases, but each purchase is a far, far more qualified customer, plus, you can almost break-even on the one-and-dones, and you may make enough money on the breakage to make it tiny profitable.
I get that tiny profitable isn't a VC's goal, but for a side project that's dying anyway, this might make the runway infinite, which you could use to rattle around and maybe find a winning model, or just let it run and not cost you much.