Akihiro Isogai was a trainee at the Jam Factory in Adelaide from 1979 to 1982, which makes him an exact contemporary of Michael Hook. He is now a major glass artist in Japan, with examples of his work in many leading galleries in that country and elsewhere including the Corning Museum. Towards the bottom of that page you reference you will see he mentions the Art Gallery of South Australia and the National Art Glass Gallery in Wagga Wagga (despite the spelling!).
There are several sites on Google with examples of his more modern works.
Your specimen dates from his time at the Jam Factory. The little bottle 9cm high with a round stopper in the photos comes from the same period.
Is yours valuable? It is an interesting historical piece from the period of early Australian art glass, so it is valuable to those like me who care. But as a meal ticket it would more likely buy you a cafeteria lunch than a big night out.
Am I greeting a fellow collector of Australian glass?
Trevor