Looking to buy a ipod to use for the bmw. How hard is it 2 hook up to the radio. I heard i need to get a aux imput or something which cost about 40 bucks which is fine but then after that do i just get the wire to hook up the ipod into the aux imput and im set. Im looking to get a 5 or 10 gb ipod because i dont have much songs. where is the cheapest place 2 get one?