I bought my Eibachs from a personal sale on my350z, but the guy I bought them from included his original invoice. It says it is from Z-1 performance, but the receipt only says $200. I don't know if they were running a special at the time or what, but he might have gotten some board discount :dunno: .
Anyways, I just installed mine this weekend and here are my views on it in case you care:
Installation is not a first time DIY. Luckily, I had a friend that knew what he was doing. If I didn't, I would have never finished. Ride is noticably better. No, I don't mean it handles better. I mean, the ride is less choppy and bouncy believe it or not. It also responds quicker, ect...the normal things springs do.
Hope I helped. I'm not really sure if I did or not... Let me know if you have any questions about them.