I have M7 Coilovers for low, they don't have and leaks. They retail for ~1800 new. These are not made anymore but if needed can be rebuilt later on down the line by a reputable suspension shop.
Can be picked up in san francisco or Santa Clara.
Vendor pages:
https://www.revworksinc.com/M7-Super...0Z_p_3087.html
https://whiteheadperformance.com/pro...an-370z-09-13/