i just checked the repair estimate from when my z got t-boned, and the replacement part for the rear quarter fender was listed at ~$800, plus the labor to cut and weld to replace the damaged one, plus paint, etc. it's possible that you may be able to find a rear clip with a fender that is in good shape for less though.
"The two seater is being joined in a few weeks by a larger two-plus-two model with a rear seat for munchkins." ~Jim Mateja, Chicago Tribune, in regards to the Z32.