| The cheap way is with a cheap deck that can be controlled by infrared.
Then get an infrared (generic) steering control adaptor. You have to mount the led somewhere it can see the deck. Doesn't work well in sun.
The right way is to get a deck that is made for a steering control adaptor. Get the right adaptor for you deck and your car and it works just like god meant it to. You need to program the buttons but instructions are good.
Next, you'll want to know what deck, what adaptor, where to buy.
If you're buying from a shop that is going to install it, let them figure it out. That’s why you pay them.
If you're a do-it-yourselfer like me, do some research.
I bought my Alpine 9855 from onlinecarstereo.com while I was working in the US. Good price, no tax, no shipping. Bought my PAC SWI-ALP interface after I got back (150 plus tax in Canada). Bought it from hookedontronix.com for 42.89 US, plus shipping, tax, duties, customs. Came to about 95 cdn.
PAC's customer service was very helpful, took a few e-mails to get the updated instructions, mine was a new car. Then when it was flakey, they helped again, told me to power it directly, not off the car harness, and then needed a cap to overcome the electrical noise (gmlan) generated by the car.
Works well now. My only complaint is that I can’t get all the functions. The Alpine is capable of 11 functions. The car only came with 8 buttons, so I had to skip some.
Good Luck!
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Alpine CDA-9887, TUA-T500HD, CHA-S634, CHA-1204 & KCA-410C
Pioneer TS-A6981, 6 x GM-5100T
Kicker 2 x CVR15,
MBQ RCE-216
PG MX2
Soundgate LanStar1
PAC SWI-ALP | 
Firebird Steering Wheel Audio Controls? 
Linear Mode
