There are HEAPS of different options depending on what you want to do with the car, what you want to spend and if you want more clearance to fit wider wheels etc. You might need to define a little more what you want the new suspension to do that it currently doesn't to help give an idea.
I had for the longest time: Koni Red's and King Springs. You can call King Springs and they will even make you a set to get what ever spring rate and ride height you want. They don't even charge a premium for the service!
For what I think you want, I would be looking at a set of reasonable shocks and them some lowered springs. Nice and easy, drop straight in, works a treat and is cheap. You can take a couple inch's out of the zed without ruining handling or comfort and still maintain legal height too. I THINK you should get away for $500-600 new, less second hand as that's what I've seen posted before, but I don't actually know.
From there, the sky is your limit. I.e I'm going Koni Yellow externally adjustable gas struts from a 300zx (I think that's what I was told), weld-on coilover sleeves, new springs and a solid captured bearing top-mount. But looking at a couple k instead of a few hundred and that's cheap for a track car!