Range from the cheapest fit a radiator £20 (AKZ Plumbing and Heating based in M14) to the dearest fit a radiator £170 (Blue-Flame Gas Services based in M18).
Comparing heating engineers estimates for fit a radiator gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes for removing and replacing a radiator in your home by posting your job to heating engineers in M7.