Range from the cheapest cat flap installation £128 (M&K Carpentry based in SE17) to the dearest cat flap installation £320 (Bspec Ltd based in E5).
Comparing carpenter and joiners estimates for installing a cat flap 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 fit a cat flap in E1 by posting a job with HaMuch and we will send it to carpenter and joiners in E1.

"Install a cat flap. My old one has stopped working so it needs to be replaced in a pvc door. I’ve ordered the same model. "
SE16
"Install a cat flap on back garden door glass"
EC1V