How much should i pay for lowering?

[BJMXR]

Hey all...

I understand the whole springs topic comes up a fair bit, ive looked through alot of threads and cant find any info on how much (ball park figure) i should be paying for King SL (front) and SSL (rear) fully installed keeping the current XR shocks. Anyone got any ideas as i dont want to pay hundreds more than is necessary. and also where you got them done and how good the service / quality of installation was?

Cheers guys...