Well I work for an authorized DEI dealer and am an installer, so how much it cost me is fractional to what it would cost you lol. Best Buy charge $410 for the 5701 and that includes basic install. Honestly, I would only take it to Best Buy if you know the installer working on your car personally, most of Best Buy has a bad reputation for sucking at installing (which for the most part is true). If you go to a mom and pop shop, I'm sure it would end up costing a little bit more, but not by much. I would say $500 is a good average estimate of what you will end up spending on just the 5701 install. Additional items such as backup battery and add on triggers will of course cost more in parts and labor anywhere. The most import part of the install is the work quality and the ability to disguise the alarm into factory wiring, that's why I stress again the importance of knowing the installer and his work.