Hi dazza I am not sure what is available in Aus but it is possible to buy new front and rear flares off the "Trade Me" site in New Zealand. As far as the clips they are still available from Nissan although expensive. I have just finished re-fitting my flares and basically used bolts and nylock nuts . These are easy to use on the rear flares as the back side is accesable. The front is more difficult to do unless you remove the guards and internal plastic liners although this is not a big job. Once you take the guards off the vehicle it is pretty simple to bolt the flares and liners to the guards before re-fitting to the vehicle. The plastic strip that goes between the guard and the flare usually shrink over time, I put mine in the oven on a low heat until they became soft and pliable and stretched them back to the original length using double sided tape to keep them stretched.
Trade Me is NZ version of E-Bay, hope this helps.

Good Luck, Lee