I bought mine from crutchfield. It's not the cheapest, but if it's just going to save $10 or so, I would much rather order from a place like critchfield.
And the guys at PAC are super nice. The info they had for my lincoln was incorrect and one of the techs helped me work it out. Very nice. Also I was getting a POP from my amp when it was turning on. I asked the PAC tech guy just cause he was an expert about car audio... and he told me it was the amp turn on from the pioneer was 12V and the amp in my lincoln wants 5V... so a 7805 and a couple caps later, no more POP. It would have taken me ages to figure that out. Great guys at PAC.