If ur lookin 4 a hk, ht or hg Monaro search country towns
you will get more value if you find an old original monaro from a country town, go off word of mouth etc.
ebay is a good resource, jus make sure u look at the vehicle prior to purchasing it, photos lie!
car magazines such as australia muschle car offer valuable information on id plates so you can check out the authenticity (i.e. whether it is a base model, gts, gts 327, etc)
check the lower sections of the front gaurds, floor sections, sections under the rear window and rear screen and also the front of the sub frame for rust
cars guide, car trader magazines, ebay, trading post r all good spots 2 look
but if ur lookin there, so is everyone else
if u want 2 get a good 1 for the right price, u have 2 get lucky or be very patient, go off word of mouth, and act fast when you hear about deals

hope this can b of some help