In these conditions, even a bias is present, offer prices existing in the media can be proxies for prices. Corrections (+/-) depending if it is a buy / sell offer are required.
(Residual land value) The sum of money available for the purchase of land can be calculated from the value of the completed development minus the costs of development (including profit).
In addition to the residual land value, land value can be obtained using several other approaches. These include (i) Sales comparison (ii) Allocation (e.g. lot values, raw land values and adjusted value to reflect density of development) (iii) Extraction and (iv) Income capitalisation ( e.g. direct capitalisation of ground rent, yield capitalisation for subdivision analysis). The particular method to be adopted will obviously be dictated by the purpose of valuation, amongst others.