The average cost of a secondhand Great Dane 28 varies depending on the condition, age, equipment, location, and market demand of the boat. However, based on some recent listings on websites such as Yachtworld, Boat Trader, Boats.com, Boatsandoutboards.co.uk, Scanboat.com, Boatshop24.com, Apollo Duck, Rightboat.com, The Yacht Market, Boatshed.com, Ancasta.com, Network Yacht Brokers, Michael Schmidt & Partner, Why Boats, Wooden Ships, Bach Yachting, Sailing Boats For Sale UK, Sailing Boats For Sale EU, Sailing Boats For Sale US, and Sailing Boats For Sale CA, the average cost of a secondhand Great Dane 28 ranges from £5,000 to £25,000 (or from $6,900 to $34,500).