I was taken by someone I know who works at a local audio shop in 2007. I paid close to $700 for them to add a Memphis Power Reference 10 to the stock system in my 2007 Accord Sedan because I was too lazy to do it myself. $550 of that was for the Memphis Power Reference 10, the 16-PR2.75, enclosure, LOC, and wiring with the remainder being install and tax. Why they charged me for a LOC when my amp had high level inputs, I'll never know.
Then again, I can't complain because when I totaled my car, the wrecker yard wouldn't let me pull the system, BUT it was damaged in the wreck anyhow. My insurance cut me a $500 check for the gear and the insurance of the person who totaled my car cut me another check for the gear, medical bills, and pain and suffering. In the end, I came out ahead financially.