Orangery Extension Prices. Orangery prices are dependent on the size, configuration, features and styling. Orangery prices can range from £7995 to £100,000+. Small timber framed orangeries are generally the cheapest whilst larger orangery extensions will typically range from £20,000 onwards.The average cost of Orangeries ranges between £20,000 and £50,0000, again this is all down to a number of factors.People deciding between a conservatory or an orangery should take note of the price differences due to the roof and overall structure.Conservatories in wood tend to be cheaper due to the pitched roof whereas an Orangery will also require a roof lantern.eople deciding between a conservatory or an orangery should take note of the price differences due to the roof and overall structure. Conservatories in wood tend to be cheaper due to the pitched roof whereas an Orangery will also require a roof lantern.