One of the more “available” sets, sometimes there’s a set on eBay. Alternatively I may have a spare set, if you are interested let me know. The first day of issue was 14 FEB 1979. There are actually 5 covers for this series, one has all 4 stamps on it, plus the 4 single covers (one for each stamp):
20c PS Canberra (stamp) / “The Great Wharf” (cachet)
35c MV Lady Denman (stamp) / “The Ferry Wharf, 1900” (cachet)
50c PS Murray River Queen (stamp) / “A Tradition of Glory” (cachet)
Set of 4 stamps / “The Great Steam Ferries” (cachet)
Some more information about the artist Otto Borchert from the Unicover website:
Otto Borchert Australian
Australian graphic designer Otto Borchert trained in Hanover, Germany, where he attended art school, sitting under the tutelage of many noted artists. He migrated to Sydney, Australia, in 1956 and in two years opened his own studio. Borchert created posters and other printed material for various worldwide distributors, including the travel industry and multi-national companies. His refined, detailed style of painting was well suited for cartography, and Borchert became known for his colorful, detailed maps and charts. His use of fine detail, brilliant color and realism works well in stamp design. Borchert has created a variety of stunning paintings for postage stamps, including his spectacular 1976 Australian Scenes Stamp Series. He has also produced a stamp series for the Australia Post, in April 1979, featuring ferries and Murray River steamers, a testament to his regard for accuracy and detail.