just in case you came here for car audio instead of car computers:
i have never purchased through dealercost, though i have seen them advertised over at diymobileaudio.com. my gear usually comes from sonic electronics-- mostly becasue they include warranties with everything--if it makes a difference to you(i know somw people prefer to get equipment from authorized sources), they are not authorized dealers for alot of brands, but include a 'sonic electronics' warranty with the products. there are plenty of online stores taht are reputable, i usually find them with search terms like 'cheap car audio' or 'discount car audio'This forum is dedicated to CarPCs and installing them in your car.
The car audio forum is dedicated to integrating your car audio system with your CarPC.
For specific questions related to car audio equipment systems that do not include CarPCs, I would recomend checking out car audio specific forums:
There is a chance that someone on here might have an answer for you, I would just hate for you to wait around for it when I know you could get an answer much quicker on a dedicated forum.