Alternators.

So i was driving today and my car died... I managed to get towed home and have had a look at the car, seems that the alternator may be gone, when it starts the battery reads 14.4 volts and then will drop to 10.2 Volts and then after about 15 minutes will go back up to 14 volts so I'm guessing that it's cutting in and out.

So how much will a auto electrician charge to replace it? I've had a look on Trade me and can pick on up from a wrecker for $50, so how easy is it to do your self, is it really just loosen off the belt, unplug and unbolt or is there more to it?

I should add that it's a 1993 Nissan Pulsar XIR

Sounds like your voltage regulator. I'm not sure about Pulsars, but some alternators have them built in. Others have them in line, so they can be replaced.
Ring up an auto sparky and see if they can tell you if its built in or not, and how much to replace.