If you don't mind that they lower the car a little, I've heard others here talk about the H&R spring kit from Tire Rack.
Here
Looks like they run $272 for a set of springs, plus whatever rubber parts you want to replace while you're in there. I'd say at least the spring perch shim/donut on each, while you have them apart.
I have a set for my SEC, but haven't gotten around to installing them yet, as my SD decided that it was attention deprived and needed to be paid attention before the SEC got any more.