Range from the cheapest Downlights installation £160 (D C Electrical based in N16) to the dearest Downlights installation £480 (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 E8.

"Downlights installation"
E9
" Downlights installation in living room and kitchen area - open plan room. Currently have 3 pendant lights and 1 x 3 small spot light in kitchen area. I would like these replaced with the downlights. I was told previously that I might need x 20. I would like in the hallway too if within my..."
EC1V