Range from the cheapest Fit a radiator £90 (S.I Gas Service and Repair based in B20) to the dearest Fit a radiator £190 (O W Plumbing & Heating based in B44).
Comparing heating engineers estimates for fitting a new radiator in B20 gives you an idea of who will be better value, but the best way to compare costs is to get actual quotes. Radiators vary in price, and additional hours will be required to make pipework changes.
What to do - Get rates and quotes for removing your old radiator and replacing it with a new radiator by posting your job to heating engineers in B20.

"Replace 5 like for like radiators "
B20
"Change 3 radiators. All 3 radiators are wider around 15-20cm. Pipes may need extending under floor boards. 1 on solid wall, 2 on plaster board. "
B6