Range from the cheapest Downlights installation £270 (Allsparkz based in SP10) to the dearest Downlights installation £410 (Peak Electrics based in SO20).
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 Test Valley.