Unless you want to install the kit yourself, you’ll need to hire a qualified professional to do it for you. The price for this service can vary widely. It counts as a customization job, so not every auto shop will agree to do it for you. Those that do can often charge well over $100/hour for their labor.
That’s why it’s important to get quotes ahead of time and compare them with other offers—that way you can be sure that you’re getting the best price.