The cheap guys won't do what you can't see. They woun't do the prep sanding, priming or surface cleaning. The "slightly different" shade will probably show up in the door frames. This will brand your car and reduce the selling price. I'd go with the body shop but there's no guarantee there either. Look at the finished cars closely in their shop and try to get some references. You've got an upscale car. You don't want it looking like an old Taurus. Your wife will NEVER repeat NEVER let you forget it! Good luck....