At that price, forget the Grouppe N subframe mounts. A decent poly setup seems it will fit all of your needs. I got the Revshift camber correction bushes for my car, they pull the subframe up toward the body to counter act a bit of the camber inducing effects of lowering the car.
Race springs are fine, but when I replaced mine with German Engineering coilover sleeves I noticed an improvement in ride quality with a stiffer spring and the ability to go lower (My car is mostly street) as well as improved handling. Around the same time as teh coilovers I also added new bushings, control arms, strut mounted sway bar endlinks (E30M3 suspension) as well so may not be a fair or direct comparison as far as the springs go.
Personally I think Delrin is overkill for most things on a car that's going to be driven on the street. A good poly part is what I prefer. That being said, I do have the Condor Speedshop delrin front control arm bushings.
What's the difference between a BMW and a porcupine?