my friend bought a Z2 (i myself have a D3 in my truck), but it was "open box" at CC and did not come with the "RCA plug" (ie the one next to the main pioneer one that has all the RCA inputs and outputs and mute wire). anyone know a good place to find those? google search brings up one vendor on ebay that has them for $40. is that reasonable? sure doesn't seem like it to me... also, any consequences of not having that hooked up and starting the unit? thanks in advance

You can call Pioneer direct and get one from them. Or try parts.pioneerelectronics.com