2002 Buick Rendezvous Question: i have a 2002 buick rend.what would be the average cost for rear spring coil?

I took my car in for new rotors the mechanic told me theres a light crack on rear coil spring that he recommended to be fixed. I was hoping to find out here first, because you guys were a big help before with my question . I certainly appreciate any help! spent enough money on the rotor job :{ this 2002 buick rendezvous is costing me. thanks for any info.