Lawyer fee for green card process?

Can somebody give me a rough number of average lawyer fees for green card application?

I talked to a lawyer the other day. He told me that he will charge different fees for PERM and I-140: $4500 for PERM and $2000 for filing I-140. He didn\'t mention fees for 485. Are these fees OK?

I have no idea about the fees so any comments or suggestions would be appreciated. Thanks a lot.