In Plants vs Zombies I am interested in earning enough gold to unlock all the minigames. I've currently got about 45,000 gold so I'm getting close to affording one. However the plants in my zen garden are demanding the gramophone, which costs 15,000. I could also buy the night zen garden for 30,000, but it's taken me a long time to earn that much so I don't want to waste it.
Does the zen garden offer a good return on investment? If I focus on improving it will I reach my goal of unlocking all the minigames faster than if I just saved my gold?