Range from the cheapest Downlights installation £240 (Future Wiring based in E17) to the dearest Downlights installation £590 (Boiler Repairs London based in E9).
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 E5.