Range from the cheapest Downlights installation £290 (TMB Electrics based in SM1) to the dearest Downlights installation £690 (Emergency Electrician in london 24 hour Grip Electric Limited based in Kt4).
Comparing electricians estimates for Downlights installation 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 installing downlights by posting a job to electricians in SM3.