Price based on using 30mm x 8mm frame and 12mm square bars (Round uprights will be cheaper by about 5%).. Also allow 30mm ground clearance. As a guide railing heads are around 130mm tall.
Standard flat railing

Length | 900mm (3ft) | 1200mm (4ft) | 1500mm (5ft) | 1800mm (6ft) | 2100mm (7ft) | 2400mm (8ft) | 2700mm (9ft) | 3000mm (10ft) |
height | ||||||||
300mm (12 inches) | £110 | £135 | £160 | £185 | £210 | £235 | £255 | £280 |
450mm(16 inches) | £125 | £155 | £185 | £215 | £235 | £265 | £295 | £325 |
600mm (24 inches) | £135 | £170 | 189 | 216 | 243 | 270 | 297 | 324 |
750mm (30 inches) | £150 | |||||||
900mm (36 inches) | £165 | |||||||
1200mm (48 inches) | £180 |

For dip down rails add £ 40 to the price of the straight railing, this is usually enough to cover the cost of making the curve and individually cutting the bars for the curve

For rise up railings add £50 to price of straight railing this is usually enough to cover individual cuts and the extra material need in the rise