Unusually, SA has the lowest priced rego in Aus lol and is a great way of funding the cat and dog management programs as well as enabling the council to contact you if your dog strays....although -and I doubt this will surprise anyone! - they charge a fair bit when they reunite you. If you are caught with your dog not wearing their tag, you could be fined. If you are caught letting your dog off-leash or breaking some other by law, they use the tag as id.
Some working dogs are charged less than pet dogs and if you are a concession card holder you might pay less. Otherwise, the fee is less if you can prove your dog is de-sexed, micro-chipped or has been obedience trained by a reputable trainer. I don't know what constitutes a reputable trainer as my dogs are feral mutts who do as they like lol! (Not really, they are gorgeous girls who do as they like!).
Don't think they give any discount for vaccinations but definately the micro-chipping,de-sexing and obedience EACH with proof.
Now, off to the beach before stupid Daylight Savings kicks in!