1. Crank Puller
2. Pin spanner (maybe)
3. Lockring Tool (You need one of these anyhow...)
4. 1/4" bearing balls
5. grease

The parts inside may actually be okay. "Clunk" usually is because it loosens. It is good to have spare parts, though. Hopefully your spindle races are in good shape.

Alternatively, instead of the pin spanner, you may need a different wrench to turn the adjustable cup. You should be able to figure this out by looking at it.

Overhauling the bottom bracket is a meditative exercise and it improves the quality of the ride. Enjoy.