Although you can indeed play this game free, I usually recommend VIP 4 as the minimum level to enjoy the game more.
I am not sure where the exact amount that takes, and money is relative to all of us, but if you can afford it, I recommend getting there by purchasing 9.99 deals on Sunday during Guild gift time to maximize purchases. You will stop running out of raid tickets and will be able to use more diamonds and stamina during contests.
If you can spare it, maybe by purchasing a little at a time over time, VIP 5 is quite nice. Anything after that is not necessary but of course helpful.