The price is inclusive of mounting and balancing. The other great part is I can rotate both sets of tires every year. I found the matching sets in the LM-25 tire and the shop that will be doing the service for me does a lot of business with sports cars. Every time I go there I see some AMG, M3/5, or other Luxury performance car, so I'm not worried about they doing any damage to the rims. I've dealt with them in the past.
A big selling point for me, even with the salt and elements being exposed to the RIMS is that I have a 100% ISF in the Summer and at 90% ISF in the Winter. When you go down to 18" and a narrow tire on the back, you lose the look and the performance when snow is not down on the ground.
I'm also a little hesitant with putting wider tires on the front of the car, than is stock.