Below is a 1971 newspaper advertisement promoting the sale of two- and three-bedroom apartments in an apartment complex located at 63 Helen Street, Lane Cove.
Two-bedroom apartments were available for sale from $17,400, and three-bedroom apartments from $20,750. According to the RBA Inflation Calculator, this would equate to spending either $232,500 or $ 274,000, respectively, in today's money.

Source: Shead Pty. Ltd. 1971. "63 Helen Street, Lane Cove" (Advertisement). The Daily Telegraph, June 12: 42.