Fiesta disks won't be much more than the pads and it's not a lot longer job to change them.
Just take the wheel off (or stick your hands through the spokes of the wheel if you can) and feel the outside edge of the disks, if you can feel a significant lip on the edge of the disks or if you can feel any large scores across the surface of the disks then you may need new disks, but otherwise I'd agree with Eddie in saying the chances are you'll just need pads.
Don't walk into a garage and tell them you think you need disks though, if you say you think you need them a lot of places will change them regardless of a need for them.