changing head units?
 

I'm sorry if this answer is somewhere else cause I know it can be so annoying when the same thing is asked by every new person all the time but I was wondering with my 2005 scion tc, if I were to put an 06 and 07 head unit in, what would I need to play my ipod from seeing as there is no official aux? I was thinking about getting an adapter for my current HU but I see stereos on ebay for pretty cheap and I'd love to have a knob instead of those annoying arrows to turn the stereo up or down.