How much does adding a curved feature cost?

Entrance canopies:
A basic atrium or entrance canopy may consist of 4 or 5 curved roof members, the cost of curving five 100 x 50 x 5 RHS would be approximately £200

Curved roofs for factory units
A set of twenty 533 Universal beams 18 metres long curved for a two pin arch for a roof would cost £60 each. (Barnshaws own building)
Picture of Site B
Superstore roof structures
A set of twenty 762 Universal beams 28 metres long curved for a three pin arch for a roof would cost £180 each. (Asda Superstores with curved roofs)