When I was shopping around for a clutch, I found the aftermarket ones way cheaper then fords OEM clutches. I got a Centreforce stage 1 clutch and installed it myself, which I did in my apartment buildings parking lot. If you have some patients and basic tools it can be done. It cost me ~$350 US do to the TOB, Clutch, and Plate. And 2 days of blood, sweat, and tears.
I hear Spec is pretty good as well, in fact next time that is what I'm going with. I did this while my car was under warrenty. I did it myself cause ford told me the clutch isn't under warrenty. Bastards. although the TOB is but they said to do the clutch as well, but I would have to pay for it, there just wouldn't be extra for the install since they would be in there already replaceing the TOB, which was squeeling like a mofo.