I've had an armrest in my Ref Sport for 9 months. I got it from a UK dealer and it has the red flecks, which kind of match the ref sport interior. It only cost me £50, so if you are paying £100, you ARE getting ripped off. It's a doddle to fit, (all you need is a screwdriver and a drill) and mine has the hole for i-pod connextions etc, even though i don't have an aux-in.
The armrest does give you a bit more storage space, you can get phone chargers etc, in it and a small bottle of water. It is can be a pain for pressing the door unlock button, but if you are worried about that, I suggest you have bigger issues
In my opinion the arm rest is a no brainer.
HTH