Zankoku coilovers look to be a great alternative.
All the Primera people are loving them at least.
Here's the details on the separate models
X1 features ride height adjustment & 12 way damper adjustment
X2 features ride height adjustment, 12 way damper adjustment & pillow ball front & rear mounts (some models pillow balls only available on front)!
Nissan Sentra B13 6 kg per mm / 4 kg per mm (336 lbs per inch / 224 lbs per inch)
Nissan Sentra B14 6 kg per mm / 4 kg per mm (336 lbs per inch / 224 lbs per inch)
Nissan Sentra B15 ?/?
NISSAN SENTRA B13
X1--> $698 picked up / $748 shipped in lower 48
X2--> $719 picked up / $769 shipped in lower 48
NISSAN SENTRA B14
X1--> $672 picked up / $722 shipped in lower 48
X2--> $719 picked up / $769 shipped in lower 48
NISSAN SENTRA B15
X1--> $672 picked up / $722 shipped in lower 48
X2--> $699 picked up / $749 shipped in lower 48
These are fantastic prices and they are no one to be found on here. I only found one person who installed them on there car and spoke about it.
Info pulled from here:
http://www.g20.net/forum/showthread.php?p=1446843#post1446843