To do it the right way, you should always install pads on a new or resurfaced set of rotors for proper break in. Nissan recommends resurfacing rotors using an on-car brake lathe, which machines the rotors parallel with the hub. New harware is typically a good idea and most premium brake pad set will come with new shims and slide plates. Cost depends on a number of factors, including shop labor rate and the price of parts and the quality of those parts. The original equipment pads are ceramic type and you should stick with that. Last type I priced a set of genuine Nissan front pads for an R51 they were around $100. I ended up getting a set of Akebono Ceramics from Rockauto.com for a lot less, but keep in mind that your mechanic is getting parts from a parts store, as opposed to online, and has to make some money on the parts. I'm not necessarily sold on the brake fluid flush if he's not opening the system, but it is a good thing to do every couple of years to get any possible moisture out of the system. One thing I will advice is to spend the money for premium pads; cheap pads tend to squeek and make a lot of dust, which usually end up covering your front wheels. For price estimates, you might try this site:
www.repairpal.com/estimator