KILLERGS4

I just purchased Apline video monitors and Valor DVD player for my LS430 2004. They were professionally installed, but I get no audio from the factory speakers, only the headphones. The installer was trying to sell me audio harness which had Ipod capabilities, but I dont need Ipod capabilities. This harness was 200 bucks! What basic harness can I purchase to get sound from my factory head unit??? Please help, I'm going back to the install shop this friday, i would like to have the part by then...