Both PAC and PIE sell auxiliary adapters for factory stereos. If you can find the right PAC adapter, you should be able to get it for around $50 or so on ebay (brand new).

As for the mount, I swear by Proclips (http://www.proclipusa.com/).

 

I had an RDS headunit in my 05, there's no garauntee the PIE will work for you, seeing as it didn't for mine... I'd look at getting the unit from Crutchfield seeing as they're easy to deal with and if it doesn't work, they'll definitely take it back and refund you the money.

I ended up returning the PIE adapter to Crutchfield and paying 300 bucks to get a deck installed with an AUX input... I'll never go back to an FM transmitter.

I'd install the deck yourself though if you could. All you need as far as I know is the mount/fillerplate, harness adapter, antenna adapter.
Reason1: I had a complete butchery on my hands, I ended up going back to get the screws they forgot to put back in from them, and the way they kinked up the harness adapter caused a loose connection, so as I was leaving the place after getting the screws back, my deck stopped working...
Reason2: The money you'd save instead of having some guy who doesn't give a rats *** about your truck install your deck is worth it.

 

definitely worth every penny because the quality is much better

 

Not just the quality over the FM transmitter though, I had a sub working off the factory deck, but when I got the new deck, the bass sounded more "pure" and punched alot harder. My Delco speakers with the sub now sound almost as good as my father's Bose system in his 2007 Sierra.

 

Been looking at this
http://www.crutchfield.com/p_105KDR6...?tp=5684&avf=N

and it has a USB connector for usb mass storages and iPods. Looks like I can hook up my player =D