If you only want one, then maybe consider adding it along side your boost gauge in another "pod". That way it doesn't look lonely on your A pillar, and you don't have to replace the whole A pillar or worry about color matching anything. The mount the boost gauge comes in is cheap also from the dealer.
i have the single a pillar pod. it was simple, yes, but personally, i dont like the look. if i was you i would definitly jsut get another stock pod and put it next to your existing stocker. you can get them from the dealer or you can get them from kimmy at speed and power development. he has a section on here and a nice website.