I remember I once had a guy come in wanted an Aux In for his Explorer, not to sure of the year. We didn't carry anything for Ford so he went to a Ford Dealership and they wound up selling a harness which plugs into the existing radio harness and includes an Aux In. I forget exactly how it works, that is if you need a Sirius, bluetooth or other Aux button on the radio included for additional options. I wasn't around when it was installed, I just talked to the guy about it and the installer who did do it. I was told it was just plug and play, real easy to install but of course the radio was with Ford removal Keys.
As for getting behind the 05+ radio, it is a ***** but because you have to remove the center console and work your way to the radio. I'd say an hour's work of labor if you've seen it or know how it's done, otherwise it's certainly doable in an afternoon.
I'd certainly ask a Ford dealer about the part, if they've heard of it or a similar piece. As for price I don't think it was that expensive, as much as you'd spend for any other product anyways.
You can also check out Scosche
. They have some Bluetooth aftermarket accessories.