My system cost about the same as both of our cars - Mine Jaguar XJR - Hers Lexus RX 330.
I bought both cars used/pre/owned (2004 models) about 4 years ago with DVD & navigation for about $70K.
I bought almost all of my system here on the gon, also pre-owned for close to the same price as both cars.
My wife loves her car & I rally love mine as well, but my system is something much more special than any car as it took much more planning & thought to put together than buying any car.
I doubt that my wife really knows what I have invested in my 2 channel system & that works for me.
She has all she needs upstairs in the home theatre & in the garage & that's what really matters most.
Remember to keep the better half happy & you'll be very happy as well.