Discounttiredirect -- order online, free shipping, $50 web discount, and $60 mail in rebate when you buy 4, puts the out the door cost right around $98/tire, not bad for a pirelli, supposedly these are the fuel efficient model too. (need to confirm)
pretty good deal considering I was going to buy a set of the 215-50/17's for $138 recently.
The cost to mount/balance will be the same no matter what, I always order my tires online and just take them to discount tire in the back of my car.
They have the deal going on for the 215-55/17's but not the proper sized 215-50/17s, go figure.