Hi William
Defintely a Council resolution needs to be sort under Section 377(h) the compulsory acquisition, purchase, sale, exchange or surrender of any land or other property (but not including the sale of items of plant or equipment). Delegation cannot be granted under this section Council approval is required.
Also Section 716 (2) Land that fails to sell at public auction may be sold by private treaty and (3) Land may be sold under this Division to the council, a councillor, a relative of a councillor, a member of staff of the council or any relative of a member of staff of the council in the case of sale by public auction, but may not be so sold in the case of sale by private treaty.
Reading all these sections in conjunction my opinion is approval needs to be sort from Council to purchase the property and a limit needs to be set on what Council will pay, Council is required to bid in the auction as it cannot purchase by private treaty.
Hope this helps