How to buy
So, you can see by now that in-car video systems can actually be optioned up to do a lot more than just play sound and video. Depending on the features you want, this type of system can be expensive, especially if you are getting it factory-installed. It can also be quite complex if you build your system up using components from various manufacturers.
There is no reason you can't custom-build your own system for your unique needs though - and save yourself a bundle of money in the process. The basic requirement is that you take the time to do your homework before buying, to make sure your system if fully compatible and gives you all the features you want, with the option of future expandability.
Spend time getting familiar with the brands, models and features you require. Check out the technical specifications and build up your knowledge and understanding of the technologies involved. Once you know exactly what you need you can buy online and either install it yourself.
These are rather complicated and typically expensive systems to buy and install, therefore, you might want to develop a good relationship with a local retailer/installer. Do your homework, read reviews, understand the technology, and you'll get the most out of your purchase. If you have a very good understanding of the technologies involved, and you know exactly what you need, and what will work with your other components, then shop around online. Whether you install it all yourself or get a professional to do it for you, is then up to you.