Range from the cheapest cat flap installation £72 (Rafs based in ME15) to the dearest cat flap installation £132 (Purdom's Bespoke Furniture based in DA4).
Comparing carpenter & 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 TN10 by posting a job with HaMuch and we will send it to carpenter & joiners in TN10.