itch.io

I would suggest going for a easier beginning, like basic pins at cheap prices, and reducing the health of the balls, so that the player can gather money easily and have a decent setup in the first levels. Then introducing more difficult balls and more costly powerups (like a healing pin that each time that is hit increases the player's health) for a more strategic middle game, you could also make it so that the pins wear and eventually break with the impact of the balls, so that the player must be paying attention at all times to replace the broken pins, and different balls doing different amounts of damage. I'm not a developer so obviously I'm commenting from the player's ignorance and not taking into account the difficulty on creating those mechanics, but that is the direction I imagine I would take with this game.