You can get them from:
http://www.autosportz.com/suspension_springs_intrax_ford.htm $269
http://www.tmengineering.net/suspension/brands/intrax/make/ford.html $210
or call Discount Tire Direct at 1-800-589-6789 for a price from them.
BTW, PM Ken (cfcsvt) from the FL forum. He has them on his SVT and from what I hear he likes them a lot.