I replaced both my fronts when they started getting pretty loud. The parts cost apx $130 per side from autozone (or you can get Ford OEM for apx $175). They're not too hard to replace, but I'll bet the dealer whacks at least $150 to $200 labor for each side. I took me about an hour each. You'll need a large deep socket for the wheel nut and a torque wrench (no other special tools are required).
The basic procedure is as follows:
#1 Remove tire
#2 Remove brake assembly and rotor (4 bolts)
#3 Remove big wheel bearing nut
#4 Remove Bearing (3 bolts) - these are little hard to get to, a universal socket helps
The one trick I learned is that you can push the half shaft back into the hub an inch or so. This gives you that little extra clearance you need to get a socket on the bearing nuts.
The wheel bearings have the ABS wheel speed sensor built in. Most new bearing come with a new sensor ... you simply unplug the old sensor when removing the old bearing and plug in the new sensor (the cable routes from the bearing to the fender wall under the hood.)
All the literature says to be very careful to retorque the wheel nut to the appropriate setting.
If you search, you may find a detailed procedure on this forum.