It depends greatly on what kind of car you have and how much labor it will be to run a 12 to 20 FOOT long power cable to the battery, properly ground the powered sub, run remote turn on wire to the radio so the sub powers on and off with the stereo. Then the tech needs to tap in to your car stereo speaker wires for the music signal. It is critical to get a clean signal or the sound will be muddy and can damage the amplifier, so an adapter is needed to make sure you get the best sound possible. So, Geek Squad is perfect. Install is inexpensive, and covered with a warranty
$100 to $150 is money well spent. -Chris (former car stereo installer).