Here is an image I found somewhere online of a pair Hanimex fins datable to the late 1970s or early 1980s:
They are datable because they have "Made in Malaysia" embossed on their blades. Hanimex must have discontinued production of these F1 Continental fins at Turnbull's plant in Sydney and outsourced their manufacture to Malaysia, which began making rubber goods around the 1970s using rubber tapped from Malaysian plantations. Hanimex would have passed their fin moulds to a rubber manufacturer in Malaysia, which proceeded to continue their production for re-export to Australia. This kind of arrangement generally lasted only a few years, after which Malaysian rubber fin manufacturers focused on training/snorkelling fins of their own design to be rebranded and imported by swim equipment distributors in the West.
As for your Hanimex Pro Continental fins, they lack a declaration of country of manufacture, which leads me to the tentative conclusion that they were not made in Australia or Malaysia. Taiwan is a possibility, but original equipment manufacturers in that country tend to mark their fins with "Taiwan" or "Made in Taiwan". Another possibility is (People's Republic of) China, where original equipment manufacturers often don't label fins with "Made in China". I suspect that if the provenance of your fins is Taiwan or China, we'll never be able to pin down the precise decade as Taiwan has been manufacturing such fins since the late 1970s and China is currently doing so.
I also found this online (
Hanimex - Camera-wiki.org - The free camera encyclopedia):
"Hanimex Corporation was founded in 1947 by Jack Hannes. Hanimex is an abbreviation for
Hannes Import Export. At some point, Hanimex Corporation became a subsidiary of Australian real estate developer, Chase Group. The subsidiary became known as Hanimex Group. In 1979, Des Franklin became the Managing Director of Hanimex. In the 1980s, under Managing Director Bill Cutbush, Hanimex acquired a number of smaller companies including Foto Island, Palcolor. In 1985, Hanimex acquired American company Vivitar, which was losing money, and in a year made the company profitable again. Due to a decline in the Australian real-estate market, Chase Group decided to sell Hanimex Group. In 1989 Hanimex was acquired by Gestetner Corporation.
Ricoh Co., Ltd. acquired Gestetner Corporation in 1996. Gestetner then changed its name to NRG Overseas Investment Ltd. On 22 April, 2004 Fuji Photo Film Co., Ltd acquired Hanimex Australasia Pty Ltd., the holding company of Hanimex Group, from NRG Overseas Investment Ltd, a group company of Ricoh Co. Ltd. Fuji discontinued use of the Hanimex name at that time but still owns the rights." One conclusion is that your fins are unlikely to be newer than 2004, because the Hanimex name became disused after that date. I can't find a date for Hanimex's departure from the diving gear business, so late seventies to early noughties is the best I can do. Valuable? Perhaps to a jet-style fin collector who wanted a relatively rare antipodean addition to what he already owned. Sorry, best I can do, but you might find out more by contacting Fuji.