If you're looking to add a sound system to your car, there are a few things you'll need to take into account. The cost of the actual equipment will be the first expense, and this can range from a few hundred to several thousand dollars depending on the quality and features you're looking for. You'll also need to factor in the cost of installation, which is usually between $100 and $200. Finally, don't forget about the cost of any additional wiring or other materials that may be required.
In total, then, you can expect to spend anywhere from $500 to $5000 or more if you want a really high-end sound system in your car. Of course, this is just a rough estimate - the actual cost will depend on a number of factors including the equipment you choose and how much work is involved in the installation process.