Wired or wireless back up cameras????

I'd like to speak to someone who really knows these things, wired or wireless. I'm looking online at Best Buy, and wonder if they might have a "dash cam geek" on site somewhere? Knowing that you're talking to an expert makes it easier to ask questions that websites can't answer.
I'll get around to it.

I remember one guy on another forum had added a wireless backup camera to his camper van, and said he could pick up wireless/wifi security cameras in some areas. I guess the wireless bands they transmit on are similar. That might be fun in some instances.