sorry to hear about this, I have had my spoiler taken and know how you feel, I have set up cctv and also used Alpha Dot on all remaining parts to try and deter would be thieves.
I would not claim through your insurance, there are often breakers and also a Ford centre on ebay which you can be more certain that the parts aren't stolen - obviously don't want to feed the demand from dodgy sellers.
I would also ring around your local scrap yard.
Somebody has mentioned a system which you can fit to your car which will page you immediately if your car is touched, I did post the other day to ask if anyone had details but don't remember getting a response - anyone know what product does this?
Hope you get it sorted soon

*Edit* Spoilers tend to go for £110 on ebay, look out for gnuine sellers and not people that happen to have them lying around

I wanted to get rid of my car when the spoiler got stolen, but having had some time to think. it could have been worse, we can only try and secure our cars as best we can.