OS 10.4 - Mac Battery and Power Problems

Hi! This is probably in the wrong place, but bare with me.

Recently, my mac kept on shutting itself down at bogus percentages. Then I learned that it was the Battery that possibly needs to be changed. However, not having money on me, I kept it on the charger.

Now, the charger cord has been wringing and splitting, so now only tape is keeping the cord together.

It's driving me crazy.

Does anyone know where a good deal online or any shops that possibly have cheap deals on a battery, or most of all, a power adapter?

Thank You.

P.S, let me remind you, that I'm in Australia. T__T.