Highest I remember reading of was Paul Trotter had a 237 somewhere in Melbourne (not sure of what centre, or when though)
Highest from Tassie would have been one of (or possibly even both) the Riley's (Ashley & Matty) had a 225 or something in Burnie once.
Highest ever for Moonah was Ray Tilla on 216.27 in the 1st Season in Centre League last year.
Not that averages really mean much in the scheme of things these days I s'pose but, it'd quite interesting to see a database of the highest averages across the country from year to year, rather like how the ABC runs thiers.