Range from the cheapest replacement of a door frame £180 (Leo McGirr Carpenter based in N7) to the dearest replacement of a door frame £480 (TFB Construction based in N7).
Comparing carpenter and joiners estimates for a new door frame 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 to replace a door frame in EC1V by posting a job with HaMuch and we will send it to carpenter and joiners in EC1V.

"New door frame"
UK
"Move door frame from current position - back inside masonry frame - allowing for a larger NEW door to be fitted"
N1