Adding Aux input to 2001 Aztek

Hi. I'd like to install an aux in adapter on my Aztek's factory stereo so I can use an ipod,cd player,etc. Through the research I did, I could not get a definite answer so I ended up going to Cruthfield and emailng their advisors. I was told that I could use an aux in adapter if my radio had a 'band' button on it. Upon looking at my stereo, it appears that I don't have this button. However, looking at the page here (http://www.crutchfield.com/App/Product/Item/Main.aspx?g=50900&i=469GM12AX2&tp=422),
it says that that aux in adapter is computable with my car. I'm getting conflicting reports from the Crutchfield 'advisors' and the website. According to their staff, my only option is to buy an fm adapter (http://www.crutchfield.com/S-1hO0wfbAvYM/App/Product/Item/Main.aspx?i=142FMMOD01) that goes into my antenna.

Once I added up the cost of the fm adapter plus the extra $20 I supposedly need, the cost comes to within a few dollars of the aux in adapter that would give me better audio quality. I just wanted to post here so I can straighten this whole thing out: can I use the aux in adapter or am I stuck with the fm adapter? Thanks.