I made this the other day after seeing the nGroove CD slot phone mount, turns out there are a few of these floating around on youtube already so it was time to make one for my GC
The parts were already available to me so there's really no expense. Tie plate, magnets from two old hard drives, 2"x2" of metal for the magnet to attach to, adhesive felt and a something to bend the tie plate with. The magnets affect the compass but you have one in the EVIC already, it doesn't mess with GPS.
My first location of choice is the spot below the driver side vent close to the radio but there is a clip in the way so I just put it in the middle. Maybe I'll adjust it closer to the driver side... we'll see, still getting the hang of it.