that sounds about right if they will be blending it into the fenders. At the bodyshop i work at he charges on avg. 350 per panel to paint it. now on a fender it will be a bit less because their smaller but you get the idea. i would check and make sure they will be using premium paints for charging a premium price, some of the cheaper paints are Omni (ppg) Nason (DuPont) and Crossfire (Martin Senour) while they arn't bad products I would want the better stuff. Also make sure they will be cutting and buffing the paint to remove and dirt nibs and excess texture.
You can get someone to paint it cheaper, shoot i've done a whole colorchange for 600 bucks, but thats because i needed something to do at home lol. anyhow a lower end shop could probably paint it for 300 with labor if you can live with the dirt specs and possible color mismatch. the prevous owner of my car had his whole bodykit painted for 300 bucks, but that doesnt include blending, and the result is if your picky the bumpers are a slightly warmer white than the rest of the car. And from personal experiance silver can be one of the toughest colors to match
If your handy with the wrench and have a 2nd helper you can replace the bumper yourself in about 30-40 minuites and save on labor, on the last mustang I did (99 or 00) if i remember right there where 2 or 3 plastic push in fasterners on the top, a couple 10mm bolts that sandwich the fender and bumper, and a row of push in fasterners on the bottom of the bumper as well as 1 screw in each corner to secure the wheel well liner. of course the 05 will probably be different but their all the same concept.
hope this helps ya
